Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.
NPIDirectory

Justin F Gainor, MD

Individual provider Internal Medicine Physician · NPI 1487813010

Justin F Gainor, MD practises Medical Oncology in Boston, Massachusetts. Graduated from Harvard Medical School in 2008, 18 years ago. Practices with The General Hospital Corporation, a 1,276-clinician group, accepts Medicare assignment and offers telehealth. Licensed in Massachusetts.

Years since qualifying
18
Trained at
Harvard Medical School
Licensed in
MA
In the registry since
2008
Specialties on file
2
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Partly verified

Some contact details are missing from the federal record.

Massachusetts General Hospital 55 Fruit St
Boston, MA 02114 Not confirmed with CMS for 13 years — call before visiting
Phone: (617) 726-2862
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Medical Oncology Physician (primary) Taxonomy 207RX0202X · Licence 245561 (MA)
Internal Medicine Physician Taxonomy 207R00000X · Licence L-236372 (MA)

Record details

NPI number1487813010
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedJune 9, 2008
Last updated in NPPESJuly 29, 2013

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyMEDICAL ONCOLOGY
Also practisesHEMATOLOGY, INTERNAL MEDICINE
Medical schoolHARVARD MEDICAL SCHOOL
Graduated 2008 (18 years in practice)
Group practice The General Hospital Corporation — 1276 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations3 on file with Medicare

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 patients171
Services billed 809 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

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.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Consulting Fee $43,070 15 payments
Compensation for services other than consulting , including serving as faculty or as a speaker at a venue other than a continuing education program $9,147 4 payments
Honoraria $2,055 1 payment
Travel and Lodging $718 2 payments · travel or lodging paid or reimbursed, such as to attend a conference
Food and Beverage $617 8 payments · a meal or drink at a meeting or visit, not a fee
Education $43 1 payment · educational material or training, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at The General Hospital Corporation

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 1276 clinicians in the practice; 12 are shown here.

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