J Brennan Cassidy, M.D.
Adult Medicine Physician · Santa Ana, CA
J Brennan Cassidy, M.D. is an adult medicine physician with a practice address in Santa Ana, California, and NPI 1528132487, issued on Nov 20, 2006. Check the license (California C30247, as entered in NPPES) on the Medical Board of California; the federal record below is the public data PlainDoctor holds for this provider.
- Name
- J Brennan Cassidy
- Credential
- M.D.
- Primary taxonomy
- Adult Medicine Physician 207QA0505X
- License number
- C30247 CA
Self-reported in NPPES; status is on the state search - Practice location
- 3929 S Bristol St, Santa Ana, CA 92704
- Phone
- (714) 662-0322
- Enumerated
- Nov 20, 2006
- Record last updated
- Jul 8, 2007 (not updated in 19 years: call before relying on the address or phone)
- Fax
- (714) 662-0329
- Entity
- Type 1 · individual
8 nearest adult medicine physician records → All 386 in California → Look up another NPI →
Verify J Brennan Cassidy in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license C30247Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
J Brennan Cassidy among 386 adult medicine physician records in California
J Brennan Cassidy, M.D. is one of 386 adult medicine physician records with a practice address in California. 69% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does not. Its NPI, issued in 2006, is newer than 3% of them.
- NPI issued2006 · 3% of these records are older, 65% newer
- In a Medicare fileNo · 69% of these records are
- In the CMS Doctors and Clinicians fileNo · 48% of these records are
- Record last updated2007 · 63% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207QA0505X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Adult Medicine Physician providers in California
There are 386 adult medicine physician records in California. No Medicare prescribing, quality score, industry payment or hospital affiliation is published for this NPI.
All 386 in California → Every provider in Santa Ana → Adult Medicine Physician nationwide →
The 8 adult medicine physician records with the nearest ZIP codes
- Ming Chen, D.O.Santa Ana, CA 927041376749101
- Lucio Loza, M.D.Santa Ana, CA 927041134352727
- Marian Bareh, M.D.Santa Ana, CA 927051518184241
- Alan Barton, M.D.Santa Ana, CA 927051831456854
- Karee Chrysovergis, FNPSanta Ana, CA 927051649805250
- Sarah Page, D.O.Santa Ana, CA 927051811332075
- Felicia Young, D.O.Santa Ana, CA 927061295898617
- Neal Schwartz, D.O.Santa Ana, CA 927011164592127
Common questions
What is J Brennan Cassidy, M.D.'s NPI number?
J Brennan Cassidy, M.D.'s National Provider Identifier (NPI) is 1528132487, issued on Nov 20, 2006. An NPI identifies a provider in billing; it is not a license.
Where is J Brennan Cassidy, M.D. located?
The NPPES record lists a practice address at 3929 S Bristol St, Santa Ana, CA, 92704. Phone: (714) 662-0322. Providers update this record themselves, so call before visiting.
How can I verify J Brennan Cassidy, M.D.'s license?
NPPES lists California license number C30247, 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.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. 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.