Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
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Zachary Gerard O'Leary, PA-C

Individual provider Physician Assistant · NPI 1083298178

Zachary Gerard O'Leary, PA-C is a Physician Assistant in Castro Valley, California. Graduated from Stanford University School of Medicine in 2021, 5 years ago. Practices with University Healthcare Alliance, a 332-clinician group, works from 2 locations, accepts Medicare assignment and offers telehealth. Licensed in California.

Years since qualifying
5
Trained at
Stanford University School of Medicine
Licensed in
CA
In the registry since
2021
What do these letters mean?
PA-C — Physician Assistant, Certified
A physician assistant who holds current national certification.

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Practice location Address checks out

20642 John Dr
Castro Valley, CA 94546-5103
Phone: (888) 924-1036
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Additional practice locations (1)

  • 5189 Hospital Rd, Mariposa, CA 95338-9524 — (907) 891-9941

Specialties & licences

Physician Assistant (primary) Taxonomy 363A00000X · Licence PA59454 (CA)

Record details

NPI number1083298178
Entity typeIndividual (Type 1)
GenderMale
Credentials PA-C
Sole proprietorNo
NPI enumeratedMay 6, 2021
Last updated in NPPESNovember 28, 2023
Certification dateNovember 28, 2023

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyPHYSICIAN ASSISTANT
Medical schoolSTANFORD UNIVERSITY SCHOOL OF MEDICINE
Graduated 2021 (5 years in practice)
Group practice University Healthcare Alliance — 332 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations3 on file with Medicare

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients131
Services billed 327 a service is one billed item, such as a visit, a test or a procedure
Average patient age75

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at University Healthcare Alliance

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 332 clinicians in the practice; 12 are shown here.

Other providers in Castro Valley