Justin F Gainor, MD

Primary specialty

Medical Oncology PhysicianTaxonomy code 207RX0202X

License

245561 Issued in MA

Practice address

Massachusetts General Hospital
55 Fruit Street
Boston, MA 02114

Phone

(617) 726-2862

NPI assigned

Jun 9, 2008

Sex

Male

Sole proprietor

No

Registry information is reported by the provider to CMS and is not verified. About this source

Specialties & licenses 3

Addresses

Medicare fee-for-service enrollment

Enrolled in MA

Eligible to order & refer

• Part B services: Yes
• Medical equipment: Yes
• Home health: Yes
• Power mobility devices: Yes
• Hospice: Yes

Green means eligible to order or refer.

Enrollment records 1

Specialty

Medical OncologyAlso: Hematology, Internal Medicine

Education

Harvard Medical School, 2008

Medicare assignment

Accepts the Medicare-approved amount as payment in full

Telehealth

Offers telehealth services

Group practices

The General Hospital CorporationGroup PAC ID 6507803806, 1,275 clinicians

Massachusetts General Physicians Organization IncGroup PAC ID 2466365820, 3,494 clinicians

Brigham and Womens Physicians Organization IncGroup PAC ID 3870405988, 2,931 clinicians

Practice addresses (Care Compare)

Hospital & facility affiliations

• Care Dimensions, Inc Hospice, Danvers, MA, CCN 221522
• Massachusetts General Hospital Hospital, Boston, MA, CCN 220071
• Brigham and Women'S Hospital Hospital, Boston, MA, CCN 220110
• Massachusetts Eye and Ear Infirmary - Hospital, Boston, MA, CCN 220075
• Brigham and Women Faulkner Hospital Hospital, Jamaica Plain, MA, CCN 220119

Medicare enrollment (NPD)

Enrolled

Credentials

Doctor of Medicine

State licenses

Practice roles

Locations

Interoperability endpoints

• Direct secure messaging: gainor.justin.mgh@direct.partners.masshiway.net

Organizations this provider is connected to: Medicare benefit reassignments (the organization bills Medicare for this provider’s services), Care Compare group memberships and National Provider Directory roles.

• Brigham & Womens Physicians Organization Inc

  • Internal Medicine Physician
  • Boston, MA
  • NPI 1033535497
  Medicare reassignment Care Compare group NPD
• Massachusetts General Physicians Organization Inc

  • Dermatology Physician
  • Boston, MA
  • NPI 1801874573

  Internal Medicine

  Medicare reassignment Care Compare group NPD
• The General Hospital Corporation

  • General Acute Care Hospital
  • Boston, MA
  • NPI 1023049236
  Medicare reassignment Care Compare group NPD
• General Hospital Corp

  • General Acute Care Hospital
  • Boston, MA
  • NPI 1508390014
  NPD
• Brigham and Womens Physicians Organization Inc

  • Diagnostic Radiology Physician
  • Boston, MA
  • NPI 1265464598
  NPD (past)

Hospitals and other facilities this clinician is affiliated with according to Medicare Care Compare.

• Care Dimensions, Inc.

  • Community Based Hospice Care Agency
  • Danvers, MA
  • NPI 1447344130
  Care Compare affiliation Name & address match
• Brigham & Womens Hospital, Inc.

  • General Acute Care Hospital
  • Boston, MA
  • NPI 1790717650
  Care Compare affiliation
• Brigham and Women'S Faulkner Hospital, Inc

  • General Acute Care Hospital
  • Boston, MA
  • NPI 1578677811
  Care Compare affiliation
• Brigham and Women'S Faulkner Hospital, Inc.

  • Psychiatric Hospital Unit
  • Boston, MA
  • NPI 1033121025
  Care Compare affiliation
• Massachusetts Eye and Ear Infirmary

  • General Acute Care Hospital
  • Boston, MA
  • NPI 1639101751
  Care Compare affiliation
• The General Hospital Corporation

  • General Acute Care Hospital
  • Boston, MA
  • NPI 1023049236
  Care Compare affiliation

The complete NPPES record for this NPI in the NPI Registry API format.

{
    "created_epoch": "1212969600000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1786406400000",
    "number": "1487813010",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "MASSACHUSETTS GENERAL HOSPITAL",
            "address_2": "55 FRUIT STREET",
            "city": "BOSTON",
            "state": "MA",
            "postal_code": "02114",
            "telephone_number": "617-724-4000"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "MASSACHUSETTS GENERAL HOSPITAL",
            "address_2": "55 FRUIT STREET",
            "city": "BOSTON",
            "state": "MA",
            "postal_code": "02114",
            "telephone_number": "617-726-2862"
        }
    ],
    "practiceLocations": [
        {
            "address_1": "75 Francis St",
            "address_purpose": "LOCATION",
            "city": "Boston",
            "state": "MA",
            "postal_code": "021156110",
            "country_code": "US",
            "telephone_number": "617-724-4000",
            "country_name": "United States",
            "address_type": "DOM"
        },
        {
            "address_1": "1153 Centre St",
            "address_purpose": "LOCATION",
            "city": "Jamaica Plain",
            "state": "MA",
            "postal_code": "021303446",
            "country_code": "US",
            "telephone_number": "617-724-4000",
            "country_name": "United States",
            "address_type": "DOM"
        }
    ],
    "basic": {
        "last_name": "GAINOR",
        "first_name": "JUSTIN",
        "middle_name": "F",
        "credential": "MD",
        "sole_proprietor": "NO",
        "sex": "M",
        "enumeration_date": "2008-06-09",
        "last_updated": "2026-08-11",
        "certification_date": "2026-08-11",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207RH0000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine, Hematology",
            "state": "MA",
            "license": "245561",
            "primary": false
        },
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "MA",
            "license": "L-236372",
            "primary": false
        },
        {
            "code": "207RX0202X",
            "taxonomy_group": "",
            "desc": "Internal Medicine, Medical Oncology",
            "state": "MA",
            "license": "245561",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": []
}

• Eric D Gaier, MD. PHD
• Gaurav D Gaiha, MD
• Aliyah Nicole Gaines, MD
• Latarsha Gaines
• Naomi Gaines, PA
• Melanie L. Gainsbury, M.D.
• Nicole Gaisford
• Henning A Gaissert, MD
• Johannah Be Gaitings-Harrod
• Stuti Paresh Gaitonde, BDS

• Medical Oncology Physician in Boston, MA
• Providers in Boston, MA by specialty
• Medical Oncology Physician in Massachusetts

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Aug 11, 2026; self-reported and not verified by CMS. Specialty names from the NUCC taxonomy.
• Medicare enrollment (CMS PECOS): enrollments, PAC IDs and benefit reassignments; Order and Referring.
• Medicare Care Compare (CMS): clinician profile, group practices, facility affiliations, MIPS scores and star ratings.
• National Provider Directory (CMS): practice roles, locations, licenses, networks and endpoints.

Verify at the official NPI Registry.