Mark E. Williams, MD
Emergency Medicine Physician · Santa Rosa, CA
Mark E. Williams, MD is an emergency medicine physician with a practice address in Santa Rosa, California, and NPI 1770661530, issued on Nov 1, 2006. Check the license (California A72120, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mark E. Williams
- Credential
- MD
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- A72120 CA
Self-reported in NPPES; status is on the state search - Practice location
- 401 Bicentennial Way, Santa Rosa, CA 95403
- Phone
- (707) 393-4800
- Enumerated
- Nov 1, 2006
- Record last updated
- Apr 5, 2024
- Medicaid ID
- 00A721200 CA
- Medicare enrollment
- Enrolled (PECOS I20240807000308); accepts Medicare assignment
- Medical or professional school
- University Of Michigan Medical School, 1996
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 401 Bicentennial Way
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Anna Ackerman, RNRegistered Nurse1376409409
- Patricia AdamsPhysical Therapist1124971825
- Hugo Aguilar, PHARMDPharmacist1992389134
- Heather Aiello, OTR/LOccupational Therapist1851155022
- Sandra Akrawi, REGISTERED DIETITIANRegistered Dietitian1790821031
- Miguel Alcala, LCSWClinical Social Worker1629857891
Verify Mark E. Williams in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A72120Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
24% more Medicare Part D claims than the average emergency medicine physician in 2024
281 Medicare Part D claims for 196 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. Brand-name drugs were 6% of claims. 35 claims were for opioids.
Most prescribed
- Ondansetron Odt27 claims
- Prednisone25 claims
- Hydrocodone-Acetaminophen17 claims
- Cefpodoxime Proxetil16 claims
- Doxycycline Monohydrate14 claims
- Cephalexin11 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through one group practice
- Hawaii Permanente Medical Group IncHonolulu, HI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mark E. Williams among 7,751 emergency medicine physician records in California
Mark E. Williams, MD is one of 7,751 emergency medicine physician records with a practice address in California. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 4% of them.
- NPI issued2006 · 4% of these records are older, 60% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 59% of these records are
- Graduated1996 · median 2011 among the 4,560 with a school on file
- Record last updated2024 · 59% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Emergency Medicine Physician providers in California
There are 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in Santa Rosa → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
- Tucker Bierbaum, M.D.Santa Rosa, CA 954031841234408
- Cyrus Colbert, MDSanta Rosa, CA 954031073697140
- Robert Duchynski, MDSanta Rosa, CA 954031538243522
- Eberle Ewing, MDSanta Rosa, CA 954031629152798
- Shawn Franklin, MDSanta Rosa, CA 954031669422507
- Stephen Fuette, MDSanta Rosa, CA 954031497840664
- Robert Galbraith, MDSanta Rosa, CA 954031194809160
- Tinh Hua, DOSanta Rosa, CA 954031871561100
Common questions
What is Mark E. Williams, MD's NPI number?
Mark E. Williams, MD's National Provider Identifier (NPI) is 1770661530, issued on Nov 1, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Mark E. Williams, MD located?
The NPPES record lists a practice address at 401 Bicentennial Way, Santa Rosa, CA, 95403. Phone: (707) 393-4800. Providers update this record themselves, so call before visiting.
How can I verify Mark E. Williams, MD's license?
NPPES lists California license number A72120, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mark E. Williams, MD prescribe under Medicare Part D?
In 2024, Mark E. Williams, MD had 281 Medicare Part D claims for 196 beneficiaries; the average among emergency medicine physician prescribers was 226. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.