James John O'Leary, M.D.
Medical Oncology Physician · Waltham, MA
James John O'Leary, M.D. is a medical oncology physician with a practice address in Waltham, Massachusetts, and NPI 1336371012, issued on Aug 14, 2009. Check the license on the Massachusetts Board of Registration in Medicine; the Medicare figures below come from public CMS files.
- Name
- James John O'Leary
- Credential
- M.D.
- Primary taxonomy
- Medical Oncology Physician 207RX0202X
- License number
- 188142 NY
Self-reported in NPPES; status is on the state search - Practice location
- 830 Winter St, Waltham, MA 02451
- Phone
- (781) 895-0600
- Enumerated
- Aug 14, 2009
- Record last updated
- Aug 14, 2009 (not updated in 17 years: call before relying on the address or phone)
- Fax
- (781) 895-0611
- Entity
- Type 1 · individual
8 nearest medical oncology physician records → All 421 in Massachusetts → Look up another NPI →
Verify James John O'Leary in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMassachusetts Board of Registration in MedicineCheck the board
- 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Industry payments in 2024: $10,750.00
2 payments; by number, the most common kind was consulting fee; the largest payer was Takeda Pharmaceuticals U.S.A., Inc. The 3,343 providers of this specialty with any payment received $11,773.47 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
James John O'Leary among 421 medical oncology physician records in Massachusetts
James John O'Leary, M.D. is one of 421 medical oncology physician records with a practice address in Massachusetts. 76% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2009, is newer than 57% of them.
- NPI issued2009 · 57% of these records are older, 39% newer
- In a Medicare fileYes · 76% of these records are
- In the CMS Doctors and Clinicians fileNo · 69% of these records are
- Record last updated2009 · 51% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RX0202X and a Massachusetts practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Medical Oncology Physician providers in Massachusetts
There are 421 medical oncology physician records in Massachusetts.
All 421 in Massachusetts → Every provider in Waltham → Medical Oncology Physician nationwide →
The 8 medical oncology physician records with the nearest ZIP codes
- Melody Craft, M.D.Waltham, MA 024511124218268
- Elgene Lim, M.D.Boston, MA 024461073817524
- Dan Longo, M.D.Brookline, MA 024451790842664
- Mark Huberman, MDNewton, MA 024591477583441
- Caroline Block, MDNewton, MA 024621851368633
- Barbara Healey, M.DNewton, MA 024621841254679
- Robert Tepper, M.D.Weston, MA 024931720101629
- Herbert Dean, M.D.Falmouth, MA 025401629135173
Common questions
What is James John O'Leary, M.D.'s NPI number?
James John O'Leary, M.D.'s National Provider Identifier (NPI) is 1336371012, issued on Aug 14, 2009. An NPI identifies a provider in billing; it is not a license.
Where is James John O'Leary, M.D. located?
The NPPES record lists a practice address at 830 Winter St, Waltham, MA, 02451. Phone: (781) 895-0600. Providers update this record themselves, so call before visiting.
How can I verify James John O'Leary, M.D.'s license?
Search the Massachusetts Board of Registration in Medicine at https://findmydoctor.mass.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
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.