Ronald Masson, M.D.
Emergency Medicine Physician · Stanford, CA
Ronald Masson, M.D. is an emergency medicine physician with a practice address in Stanford, California, and NPI 1568738904, issued on Mar 30, 2012. Check the license (California A126419, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Ronald Masson
- Credential
- M.D.
- Primary taxonomy
- Emergency Medicine Physician 207P00000X
- License number
- A126419 CA
Self-reported in NPPES; status is on the state search - Practice location
- 300 Pasteur Dr, Stanford, CA 94305
- Phone
- (650) 723-9215
- Enumerated
- Mar 30, 2012
- Record last updated
- Dec 17, 2021 (not updated in 5 years: call before relying on the address or phone)
- Medicare enrollment
- Enrolled (PECOS I20150922002856); accepts Medicare assignment
- Medical or professional school
- University Of Vermont College Of Medicine, 2012
- Entity
- Type 1 · individual
8 nearest emergency medicine physician records → All 7,751 in California → Look up another NPI →
Also registered at 300 Pasteur Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Ronald Masson in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A126419Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
18% fewer Medicare Part D claims than the average emergency medicine physician in 2024
186 Medicare Part D claims for 119 beneficiaries, against an average of 226 among the 54,106 providers of this specialty who prescribed in Part D. Brand-name drugs were 6% of claims. 33 claims were for opioids.
Most prescribed
- Ondansetron Odt18 claims
- Hydrocodone-Acetaminophen15 claims
- Oxycodone Hcl12 claims
- Cefpodoxime Proxetil11 claims
- Fenofibrate11 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.
Bills Medicare through one group practice
- Permanente Medical Group IncFresno, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Ronald Masson among 7,751 emergency medicine physician records in California
Ronald Masson, M.D. is one of 7,751 emergency medicine physician records with a practice address in California. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2012, is newer than 63% of them.
- NPI issued2012 · 63% of these records are older, 34% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 59% of these records are
- Graduated2012 · median 2011 among the 4,560 with a school on file
- Record last updated2021 · 59% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207P00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
163 emergency medicine physician records list a practice address in Stanford
They are 163 of the 5,606 NPPES records with a practice address in Stanford, and 7,751 emergency medicine physician records in California.
All 7,751 in California → Every provider in Stanford → Emergency Medicine Physician nationwide →
The 8 emergency medicine physician records with the nearest ZIP codes
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- Ian Ferguson, D.O.Stanford, CA 943051265495345
- Marc Gautreau, MDStanford, CA 943051932182185
- David Ghilarducci, MDStanford, CA 943051861435661
- Michael Gisondi, MDStanford, CA 943051659317121
- Prasanthi Govindarajan, MDStanford, CA 943051205879517
- Grant Lipman, M.DStanford, CA 943051255374005
Common questions
What is Ronald Masson, M.D.'s NPI number?
Ronald Masson, M.D.'s National Provider Identifier (NPI) is 1568738904, issued on Mar 30, 2012. An NPI identifies a provider in billing; it is not a license.
Where is Ronald Masson, M.D. located?
The NPPES record lists a practice address at 300 Pasteur Dr, Stanford, CA, 94305. Phone: (650) 723-9215. Providers update this record themselves, so call before visiting.
How can I verify Ronald Masson, M.D.'s license?
NPPES lists California license number A126419, 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 Ronald Masson, M.D. prescribe under Medicare Part D?
In 2024, Ronald Masson, M.D. had 186 Medicare Part D claims for 119 beneficiaries; the average among emergency medicine physician prescribers was 226. 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.