Gregory James Zahner, MD
Internal Medicine Physician · San Francisco, CA
Gregory James Zahner, MD is an internal medicine physician with a practice address in San Francisco, California, and NPI 1427685767, issued on Mar 26, 2020. Check the license (California A201693, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Gregory James Zahner
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License numbers
- A201693 CA
1013382 MA
Self-reported in NPPES; status is on the state search - Practice location
- 505 Parnassus Ave, San Francisco, CA 94143
- Phone
- (415) 476-1000
- Enumerated
- Mar 26, 2020
- Record last updated
- Aug 8, 2025
- Medicare enrollment
- Enrolled (PECOS I20250625004143); accepts Medicare assignment
- Medical or professional school
- University Of California, San Francisco School Of Medicine, 2020
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 505 Parnassus Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Gregory James Zahner in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A201693Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
99% fewer Medicare Part D claims than the average internal medicine physician in 2024
41 Medicare Part D claims, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
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
- Regents OF The University OF CaliforniaSan Francisco, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Gregory James Zahner among 17,696 internal medicine physician records in California
Gregory James Zahner, MD is one of 17,696 internal medicine physician records with a practice address in California. 79% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2020, is newer than 89% of them.
- NPI issued2020 · 89% of these records are older, 8% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2020 · median 2004 among the 11,065 with a school on file
- Record last updated2025 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
1,318 internal medicine physician records list a practice address in San Francisco
They are 1,318 of the 38,143 NPPES records with a practice address in San Francisco, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in San Francisco → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
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- Katherine Julian, MDSan Francisco, CA 941431003879826
- John Kane, MDSan Francisco, CA 941431467416461
- Suneil Koliwad, M.D., PH.D.San Francisco, CA 941431225006687
- Bernard Lo, MDSan Francisco, CA 941431184688137
- Stephen McPhee, MDSan Francisco, CA 941431124082490
- Andrew Posselt, MDSan Francisco, CA 941431235193616
Common questions
What is Gregory James Zahner, MD's NPI number?
Gregory James Zahner, MD's National Provider Identifier (NPI) is 1427685767, issued on Mar 26, 2020. An NPI identifies a provider in billing; it is not a license.
Where is Gregory James Zahner, MD located?
The NPPES record lists a practice address at 505 Parnassus Ave, San Francisco, CA, 94143. Phone: (415) 476-1000. Providers update this record themselves, so call before visiting.
How can I verify Gregory James Zahner, MD's license?
NPPES lists California license number A201693, 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 Gregory James Zahner, MD prescribe under Medicare Part D?
In 2024, Gregory James Zahner, MD had 41 Medicare Part D claims; the average among internal medicine physician prescribers was 3,176. 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.