Dr. Mark E. Williams, MD
- Medicare services, 2023
- 13
- Medicare patients, 2024
- 12
- Part D claims, 2024
- 281
- Hospital affiliations
- 1
- Industry payments
- $38
- Practice address
- 401 Bicentennial Way, Santa Rosa, CA 95403
- Practice phone
- Call (707) 571-4000
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Find Dr. Williams' professional email, personal email and mobile number
Dmand AI checks each channel through healthcare-specific waterfall enrichment. See what is on file with a free account, with practice phones, licenses and affiliations.
Dr. Mark E. Williams is an emergency medicine physician in Santa Rosa, California
Dr. Williams practices at Santa Rosa Medical Center in Santa Rosa, California, part of Kaiser Permanente.
Dr. Williams' NPI, 1770661530, was assigned on November 1, 2006. Dr. Williams graduated from University Of Michigan Medical School in 1996. Dr. Williams' California license number on file is A72120.
- NPI
- 1770661530NPI Registry (opens in a new tab)
- NPI enumeration date
- November 1, 2006
- NPI status
- Active
- Practice phone
- (707) 571-4000
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 56
- Medical school graduation
- 1996
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Affiliation Data
Dr. Mark E. Williams practices at Santa Rosa Medical Center in Santa Rosa, California
Dr. Williams' primary practice is Santa Rosa Medical Center, at 401 Bicentennial Way, Santa Rosa, CA 95403 in Sonoma County. The practice phone is (707) 571-4000.
- Santa Rosa Medical Center401 Bicentennial Way, Santa Rosa, CA 95403 · Sonoma CountyPhone(707) 571-4000
Source: Dmand AI Affiliation Data
Dr. Mark E. Williams is affiliated with 1 site of care and 2 medical groups
Dr. Williams' primary practice is Santa Rosa Medical Center in Santa Rosa, California, part of Kaiser Permanente. The medical group on file is The Permanente Medical Group, Inc. Dmand AI also links Dr. Williams to 1 more medical group, named with a free account.
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dr. Mark E. Williams' practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Williams practices. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Santa Rosa Medical Center | Available with a free account |
| +1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Mark E. Williams is one of 7,423 emergency medicine physicians in California
Emergency medicine is Dr. Williams' primary specialty in the NPI Registry, under taxonomy code 207P00000X. Dr. Williams is board certified in emergency medicine by the American Board of Emergency Medicine. Dmand AI has Dr. Williams' licenses on file in 3 states: California, Hawaii and Rhode Island.
Specialties and state licenses
- Emergency medicine, CaliforniaPrimary
- Hawaii license
- Rhode Island license
Emergency medicine physicians near Dr. Williams
Counts of emergency medicine physicians with a Dmand AI profile, by place and practice. Each opens the list.
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Peer Benchmarks
Dr. Mark E. Williams billed Medicare for 13 services in 2023
CMS data shows 13 Medicare services from Dr. Williams across 1 procedure code in 2023, for 12 Medicare patients. Medicare paid $1,159 for them. Every service was in a facility, such as a hospital, rather than an office.
Dr. Williams' Medicare services by type, 2022 to 2023
- 2022
- 2023
- Office and hospital visits
- 2022: 132023: 13No change
Dr. Williams compared with the California median for emergency medicine physicians, 2023
- Dr. Williams
- California median
- Medicare services
- 13vs 26595% below
- Medicare patients
- 12vs 24395% below
- Part D claims
- 121vs 6295% above
Medians across 7,079 emergency medicine physicians in California with Dmand AI profiles that report each measure.
Dr. Williams' most billed Medicare procedure codes, 2023
CMS publishes codes billed for 11 or more Medicare patients. Each label is the code family; CPT descriptions are licensed by the AMA.
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Medicare shows one payer. Book a meeting to get commercial claims data for Dr. Williams and other emergency medicine physicians in California.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. Mark E. Williams treated 12 Medicare patients in 2024, average age 62
CMS counts 12 Medicare patients who saw Dr. Williams in 2024. Their average risk score is 1.52, where 1.00 is the Medicare average, so they are sicker than most Medicare patients.
Across all payers, Dmand AI patient panel data puts Dr. Williams' median patient age at 37, with 55% women.
Dr. Williams' patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 37
Patient panel by sex, all payers
- Women55%
- Men44%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. Mark E. Williams wrote 281 Medicare Part D claims in 2024
In 2024, Dr. Williams wrote 281 Medicare Part D claims for 196 patients. 94% of them were for generic drugs. CMS names the drug for 121 of them, across 7 drugs with 11 or more claims each, at $1,570 in total drug cost. In 2023, CMS named 144 claims across 9 drugs.
Dr. Williams' Part D claims by kind of drug, 2024
- Generic263 claims94%
- Brand-name18 claims6%
Dr. Williams' most prescribed drugs by claims, 2024
CMS names a drug when it has 11 or more claims. Share is of the claims for drugs CMS names.
Drug classes CMS tracks in Dr. Williams' Part D claims, 2024
- Opioids12%35 of 281 claims
- Antibiotics27%76 of 281 claims
Share of all Part D claims for each drug class CMS reports on. Classes with no claims are left out.
Part D claims for drugs CMS names, 2023 to 2024
- 2023
- 2024
- Claims for drugs CMS names
- 2023: 1442024: 12116%
Drugs named by CMS: 7 in 2024, 9 in 2023.
Sources: Medicare Part D Prescribers - by Provider and Drug (CMS), 2024 data, released May 6, 2026; and Medicare Part D Prescribers - by Provider (CMS), 2024 data
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Dr. Mark E. Williams received $38 in industry payments in 2019
CMS Open Payments shows 2 general payments to Dr. Williams from 1 drug or device company in 2019. Consulting fees make up the largest share, 100% of the total. Z-Medica, LLC paid the most, $38.
Companies that paid Dr. Williams the most, 2019 to 2019
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. Mark E. Williams graduated from University Of Michigan Medical School
Dr. Williams graduated from University Of Michigan Medical School in 1996. Dr. Williams is a member of ACEP.
- Medical school
- Board certified in emergency medicine
Source: Dmand AI Professional Profile Data
Dr. Mark E. Williams accepts plans from 2 insurance carriers
Dr. Williams is in network with 2 carriers, including Kaiser Permanente and CMS Medicare. EPO plans come from the most carriers, 1. Check the plan with the practice before a visit.
- Kaiser Permanente
- CMS Medicare
Plan types Dr. Williams accepts, by number of carriers
- EPO1
- HMO1
- Medicare1
- POS1
Source: Dmand AI Insurance Network Data
Sources for Dr. Mark E. Williams's profile data
| Data on this page | Source |
|---|---|
| NPI, name, sex, specialty and licenses | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Professional Profile Data |
| Practice locations and phone | Dmand AI Affiliation Data |
| Primary practice, affiliations and health system | Dmand AI Affiliation DataDmand AI Org Hierarchy Data |
| Medicare services and procedure codes | Medicare Physician & Other Practitioners - by Provider and Service (CMS) (opens in a new tab) |
| State medians for the same specialty | Dmand AI Peer Benchmarks |
| Medicare patients and the all-payer patient panel | Dmand AI Patient Panel DataMedicare Physician & Other Practitioners - by Provider (CMS) (opens in a new tab) |
| Part D prescribing | Medicare Part D Prescribers - by Provider and Drug (CMS) (opens in a new tab)Medicare Part D Prescribers - by Provider (CMS) (opens in a new tab) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| Insurance carriers and plan types | Dmand AI Insurance Network Data |
| EHR at each practice site | Dmand AI Technology Install Data |
| Similar physicians | Dmand AI Affiliation Data |
Data last refreshed October 2026Report an inaccuracyRemove my information
FAQ
Frequently asked questions about Dr. Mark E. Williams
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Dr. Mark E. Williams' NPI number?
Dr. Mark E. Williams' NPI number is 1770661530. It was assigned on November 1, 2006, and it is active in the NPI Registry.
What kind of doctor is Dr. Mark E. Williams?
Dr. Mark E. Williams is an emergency medicine physician in Santa Rosa, California. The primary specialty in the NPI Registry is Emergency Medicine Physician (taxonomy code 207P00000X).
Where does Dr. Mark E. Williams practice?
Dr. Williams practices at 401 Bicentennial Way, Santa Rosa, CA 95403. Dr. Williams' primary practice is Santa Rosa Medical Center in Santa Rosa, California, part of Kaiser Permanente. Dmand AI also links Dr. Williams to 1 medical group.
What is Dr. Mark E. Williams' office phone number?
The practice phone on file for Dr. Williams is (707) 571-4000.
What is Dr. Mark E. Williams' medical license number?
Dr. Williams' California license number on file is A72120, one of the licenses on file in 3 states.
Which states has Dr. Mark E. Williams been licensed in?
Dmand AI has state licenses on file for Dr. Williams in California (2000 to 2025), Hawaii (2024 to 2026) and Rhode Island (1997 to 2000).
Which hospitals is Dr. Mark E. Williams affiliated with?
Dr. Williams practices at Santa Rosa Medical Center in Santa Rosa, California.
What medical group is Dr. Mark E. Williams part of?
Dr. Williams is linked to The Permanente Medical Group, Inc. Dmand AI links Dr. Williams to 1 more medical group.
Does Dr. Mark E. Williams accept Medicare?
Yes. CMS data shows Dr. Williams billed Medicare for 13 services in 2023.
How many Medicare patients does Dr. Mark E. Williams see?
CMS counts 12 Medicare patients who saw Dr. Williams in 2024, with an average age of 62.
Show 7 more questionsShow fewer questions
Is Dr. Mark E. Williams board certified?
Yes. Dr. Williams is board certified in emergency medicine by the American Board of Emergency Medicine.
What services does Dr. Mark E. Williams bill to Medicare?
In 2023, Dr. Williams' most billed Medicare services were emergency department visit (99285).
Where did Dr. Mark E. Williams go to medical school?
Dr. Williams graduated from University Of Michigan Medical School in 1996.
What drugs does Dr. Mark E. Williams prescribe most?
In 2024 Medicare Part D data, Dr. Williams' most prescribed drugs by claims were Ondansetron ODT, Prednisone and Hydrocodone-Acetaminophen.
Has Dr. Mark E. Williams received payments from drug or device companies?
CMS Open Payments shows $38 in general payments to Dr. Williams from 1 company from 2019 to 2019. The largest total came from Z-Medica, LLC.
How long has Dr. Mark E. Williams been practicing?
Dr. Williams graduated from medical school in 1996, 30 years ago.
What insurance does Dr. Mark E. Williams accept?
Dr. Williams is in network with 2 carriers, including Kaiser Permanente and CMS Medicare. EPO plans come from the most carriers, 1. Check the plan with the practice before a visit.
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