Jay W. Marks, MD
Gastroenterology Physician · Los Angeles, CA
Jay W. Marks, MD is a gastroenterology physician with a practice address in Los Angeles, California, and NPI 1003871914, issued on Apr 20, 2006. Check the license (California G21318, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Jay W. Marks
- Credential
- MD
- Primary taxonomy
- Gastroenterology Physician 207RG0100X
- License number
- G21318 CA
Self-reported in NPPES; status is on the state search - Practice location
- 8635 W 3RD St, Los Angeles, CA 90048
- Phone
- (323) 469-4499
- Enumerated
- Apr 20, 2006
- Record last updated
- Feb 4, 2013 (not updated in 13 years: call before relying on the address or phone)
- Medicaid ID
- 00G213181 CA
- Entity
- Type 1 · individual
8 nearest gastroenterology physician records → All 2,140 in California → Look up another NPI →
Also registered at 8635 W 3RD St
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Jay W. Marks in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G21318Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
94% fewer Medicare Part D claims than the average gastroenterology physician in 2024
45 Medicare Part D claims, against an average of 811 among the 16,445 providers of this specialty who prescribed in Part D. Brand-name drugs were 29% of 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.
Jay W. Marks among 2,140 gastroenterology physician records in California
Jay W. Marks, MD is one of 2,140 gastroenterology physician records with a practice address in California. 83% 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 7% of them.
- NPI issued2006 · 7% of these records are older, 48% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileNo · 72% of these records are
- Record last updated2013 · 60% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RG0100X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Gastroenterology Physician providers in California
There are 2,140 gastroenterology physician records in California.
All 2,140 in California → Every provider in Los Angeles → Gastroenterology Physician nationwide →
The 8 gastroenterology physician records with the nearest ZIP codes
- Maria Abreu, M.D.West Hollywood, CA 900481598793374
- David Cohen, MD PHDWest Hollywood, CA 900481881650133
- Jerome Goldwasser, M.D.Los Angeles, CA 900481831103506
- Simon Lo, M.D.Los Angeles, CA 900481255368874
- Gil Melmed, M.D.Los Angeles, CA 900481336102524
- Mark Pimentel, M.D.Los Angeles, CA 900481750319356
- Said Rahban, MDLos Angeles, CA 900481205902202
- Mamatha Sadda, M.D.Los Angeles, CA 900481255412854
Common questions
What is Jay W. Marks, MD's NPI number?
Jay W. Marks, MD's National Provider Identifier (NPI) is 1003871914, issued on Apr 20, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Jay W. Marks, MD located?
The NPPES record lists a practice address at 8635 W 3RD St, Los Angeles, CA, 90048. Phone: (323) 469-4499. Providers update this record themselves, so call before visiting.
How can I verify Jay W. Marks, MD's license?
NPPES lists California license number G21318, 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 Jay W. Marks, MD prescribe under Medicare Part D?
In 2024, Jay W. Marks, MD had 45 Medicare Part D claims; the average among gastroenterology physician prescribers was 811. 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.