William Yoon, DO
NPI 1770650509 · Family Medicine Physician · Fontana, CA
Enrolled with Medicare as Practitioner - Family Practice · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Yoon, DO is a Family Medicine Physician provider in Fontana, CA (NPI 1770650509).
Provider details
- NPI number
- 1770650509
- Entity type
- Individual
- Primary specialty
- Family Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- DO
- Sex
- Male
- Sole proprietor
- No
- License
- 20A7753 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 88 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 660 | 278 |
| Lisinopril | 319 | 143 |
| Amlodipine Besylate | 276 | 124 |
| Losartan Potassium | 241 | 96 |
| Rosuvastatin Calcium | 230 | 95 |
| Metformin Hclbrand: Metformin Hcl Er | 185 | 69 |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-11-29
- Last updated
- 2021-11-30
Frequently asked questions
- What is William Yoon's NPI number?
- William Yoon's National Provider Identifier (NPI) is 1770650509, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Yoon's specialty?
- William Yoon is listed in the NPPES registry with a primary specialty of Family Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is William Yoon located?
- William Yoon's practice location on file with NPPES is 9961 Sierra Ave, Fontana, CA 92335-6720.
- What is William Yoon's phone number?
- The practice phone number listed in the NPPES registry for William Yoon is (909) 427-3910.
- Does William Yoon accept Medicare?
- William Yoon is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Yoon's NPI active?
- Yes — William Yoon's NPI (1770650509) is active in the NPPES registry as of the last update on 2021-11-30.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.