William B. Downs, M.D.
Occupational Medicine Physician · Ontario, CA
William B. Downs, M.D. is an occupational medicine physician with a practice address in Ontario, California, and NPI 1851593636, issued on Jun 4, 2007. Check the license (California G39617, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- William B. Downs
- Credential
- M.D.
- Primary taxonomy
- Occupational Medicine Physician 2083X0100X
- License number
- G39617 CA
Self-reported in NPPES; status is on the state search - Practice location
- 1101 S Milliken Ave, Ontario, CA 91761
- Phone
- (615) 778-4066
- Enumerated
- Jun 4, 2007
- Record last updated
- Oct 7, 2009 (not updated in 17 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest occupational medicine physician records → All 415 in California → Look up another NPI →
Also registered at 1101 S Milliken Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Michelle Martin, P.T.Physical Therapist1598880502
- Christine Nator, P.T.Physical Therapist1124143151
- Jay PatelPhysical Therapist1528917416
- Nilda Torreflores, PT.Physical Therapist1790800803
Verify William B. Downs in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G39617Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
98% fewer Medicare Part D claims than the average occupational medicine physician in 2024
12 Medicare Part D claims, against an average of 794 among the 463 providers of this specialty who prescribed in Part D. Brand-name drugs were 0% of claims.
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
William B. Downs among 415 occupational medicine physician records in California
William B. Downs, M.D. is one of 415 occupational medicine physician records with a practice address in California. 30% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2007, is newer than 43% of them.
- NPI issued2007 · 43% of these records are older, 31% newer
- In a Medicare fileYes · 30% of these records are
- In the CMS Doctors and Clinicians fileNo · 12% of these records are
- Record last updated2009 · 75% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 2083X0100X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Occupational Medicine Physician providers in California
There are 415 occupational medicine physician records in California.
All 415 in California → Every provider in Ontario → Occupational Medicine Physician nationwide →
The 8 occupational medicine physician records with the nearest ZIP codes
- Patricia Fernandez, M.D.Ontario, CA 917611528254240
- Gilbert Bush, MEDICAL DOCTOROntario, CA 917621669578241
- Leon Bybee, M.D.Pomona, CA 917661043331697
- Brian BallardPomona, CA 917671497218739
- Dionisio Lazaro, M.D.City Of Industry, CA 917481508153842
- Clark Robbins, M.D.Rowland Heights, CA 917481902024136
- Priyanka Bhanot, M.D.City Of Industry, CA 917461326210246
- Amarilda Christensen, M.D.Rancho Cucamonga, CA 917301649476565
Common questions
What is William B. Downs, M.D.'s NPI number?
William B. Downs, M.D.'s National Provider Identifier (NPI) is 1851593636, issued on Jun 4, 2007. An NPI identifies a provider in billing; it is not a license.
Where is William B. Downs, M.D. located?
The NPPES record lists a practice address at 1101 S Milliken Ave, Ontario, CA, 91761. Phone: (615) 778-4066. Providers update this record themselves, so call before visiting.
How can I verify William B. Downs, M.D.'s license?
NPPES lists California license number G39617, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does William B. Downs, M.D. prescribe under Medicare Part D?
In 2024, William B. Downs, M.D. had 12 Medicare Part D claims; the average among occupational medicine physician prescribers was 794. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.