Quick answers
- Which hospitals does Mathias Masem work at?
- Medicare's official clinician data lists Mathias Masem at 4 hospitals: Alta Bates Summit Medical Center, Alta Bates Summit Medical Center - Alta Bates Camp…, John Muir Medical Center - Walnut Creek Campus and UCSF Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mathias Masem see patients?
- Medicare's clinician data lists 4 practice locations, including San Francisco, CA and Oakland, CA. Call before your visit to confirm the address.
- What is Mathias Masem's specialty?
- Medicare lists Orthopedic Surgery as the primary specialty.
- Does Mathias Masem accept Medicare assignment?
- Yes. Medicare's clinician data says Mathias Masem accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- Does Mathias Masem offer telehealth?
- Medicare's clinician data says Mathias Masem offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Mathias Masem?
- (415) 476-1000, as listed in official Medicare / NPI Registry data.
- What is Mathias Masem's NPI number?
- 1508810938. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Mathias Masem works
Medicare's Facility Affiliation Data lists Mathias Masem at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Alta Bates Summit Medical CenterOakland, CA · Acute Care Hospital · CCN 050043
- Alta Bates Summit Medical Center - Alta Bates Camp…Berkeley, CA · Acute Care Hospital · CCN 050305
- John Muir Medical Center - Walnut Creek CampusWalnut Creek, CA · Acute Care Hospital · CCN 050180
- UCSF Medical CenterSan Francisco, CA · Acute Care Hospital · CCN 050454
Practice locations
Addresses where Mathias Masem is enrolled with Medicare (CMS data updated 2026-10-02).
- 1600 Divisadero StSan Francisco, CA 94115 (415) 476‑1000
- 2330 Post StSan Francisco, CA 94115 (415) 476‑4029
- 400 Parnassus AveSan Francisco, CA 94143
- 80 Grand Ave, Suite 600Oakland, CA 94612 (510) 763‑0884
Group practices
Medicare enrollment lists Mathias Masem as a member of these groups (CMS data updated 2026-10-02).
- University of California San Francisco1,839 clinicians in the group
- UCSF Medical Group Business Services1,598 clinicians in the group
- Mathias Masem MD2 clinicians in the group
Specialties
- Orthopedic Surgeryprimary
Other orthopedic surgeons in San Francisco
Clinicians with the same Medicare primary specialty in San Francisco, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Minnesota Medical School |
| Graduation year | 1975 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1508810938 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians