Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

William W. Yoon, DO

Individual provider Family Medicine Physician · NPI 1770650509

William W. Yoon, DO is a Family Medicine Physician in Fontana, California. Licensed in California. Registered with an NPI since 2006.

Licensed in
CA
In the registry since
2006
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

See every abbreviation used in this directory →

Claim this listing Report a problem Suggest an edit

Practice location Address checks out

9961 Sierra Ave
Fontana, CA 92335-6720
Phone: (909) 427-3910
Show map & directions

Directions in Google Maps · Apple Maps · OpenStreetMap

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Family Medicine Physician (primary) Taxonomy 207Q00000X · Licence 20A7753 (CA)

Record details

NPI number1770650509
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedNovember 29, 2006
Last updated in NPPESNovember 30, 2021

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 patients13
Services billed 18 a service is one billed item, such as a visit, a test or a procedure
Average patient age60

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.

Other providers in Fontana