Quick answers
- Which hospitals does William S. Sun work at?
- Medicare's official clinician data lists William S. Sun at 5 hospitals: Adventist Health Sierra Vista, Adventist Health Simi Valley, Adventist Health Twin Cities, Emanate Health Inter-Community Hospital and Santa Clara Valley Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does William S. Sun see patients?
- Medicare's clinician data lists 3 practice locations, including Fresno, CA and San Jose, CA. Call before your visit to confirm the address.
- What is William S. Sun's specialty?
- Medicare lists Internal Medicine as the primary specialty.
- Does William S. Sun accept Medicare assignment?
- Yes. Medicare's clinician data says William S. Sun 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.
- What is the phone number for William S. Sun?
- (559) 450-3000, as listed in official Medicare / NPI Registry data.
- What is William S. Sun's NPI number?
- 1649777616. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where William S. Sun works
Medicare's Facility Affiliation Data lists William S. Sun at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Adventist Health Sierra VistaSan Luis Obispo, CA · Acute Care Hospital · CCN 050506
- Adventist Health Simi ValleySimi Valley, CA · Acute Care Hospital · CCN 050236
- Adventist Health Twin CitiesTempleton, CA · Acute Care Hospital · CCN 050633
- Emanate Health Inter-Community HospitalCovina, CA · Acute Care Hospital · CCN 050382
- Santa Clara Valley Medical CenterSan Jose, CA · Acute Care Hospital · CCN 050038
Practice locations
Addresses where William S. Sun is enrolled with Medicare (CMS data updated 2026-10-02).
- 1303 E Herndon AveFresno, CA 93720 (559) 450‑3000
- 751 S Bascom AveSan Jose, CA 95128 (408) 885‑5000
- 751 S Bascom Ave, Santa Clara Vly MedSan Jose, CA 95128 (408) 885‑5000
Group practices
Medicare enrollment lists William S. Sun as a member of these groups (CMS data updated 2026-10-02).
- Galen Inpatient Physicians PC1,077 clinicians in the group
- County of Santa Clara1,022 clinicians in the group
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Fresno
Clinicians with the same Medicare primary specialty in Fresno, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2018 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1649777616 |
| 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