NPIMap

Individual provider Active NPI

Holly Ann Mazur, M.D.

  • Internal Medicine Physician
  • Acton, MA
National Provider Identifier
1295780617
Registry record updated Sep 16, 2026
On this page

Key facts

NPPES NPI Registry
Primary specialty
Internal Medicine PhysicianTaxonomy code 207R00000X
License
81939 Issued in MA
Practice address
321 Main St
Acton, MA 01720-3799
Phone
(978) 635-8700
Fax
(978) 635-8923
NPI assigned
May 24, 2006
Reactivated
Sep 16, 2026
Last updated
Sep 16, 2026By the provider in NPPES
Sex
Female
Sole proprietor
No

NPPES NPI Registry

Updated by the provider on Sep 16, 2026

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

Specialties & licenses 2

Specialty (taxonomy)CodeLicenseStatePrimary
Internal Medicine Physician 207R00000X 61790 CT
Internal Medicine Physician 207R00000X 81939 MA Primary

Addresses

Primary practice location

321 Main St
Acton, MA 01720-3799

Mailing address

321 Main St
Acton, MA 01720-3799
Phone (978) 635-8700

Other names 1

  • Holly Ann Enterline Former name

Medicare participation

Medicare enrollment files
Medicare fee-for-service enrollment
Not listed in the public Medicare enrollment file

Care Compare profile

Medicare Care Compare
Specialty
Internal Medicine
Education
Tufts University School of Medicine, 1992
Medicare assignment
Accepts the Medicare-approved amount as payment in full

Practice addresses (Care Compare)

87 N Main St
Leominster, MA 01453-5507

Hospital & facility affiliations

Merit-based Incentive Payment System (MIPS)

Final score
87.03 of 100Reported as group
Quality
86.03
Promoting interoperability
99
Improvement activities
40
Cost
71.56

National Provider Directory

National Provider Directory
Medicare enrollment (NPD)
Enrolled
Credentials
Doctor of Medicine

State licenses

LicenseStateTypeSpecialty
81939MAMDInternal Medicine Physician

Practice roles

OrganizationSpecialtyStatusNew patients
Family Medical & Maternity Care PC CurrentSince Aug 19, 2024 Accepting new patients
Bernard a Westerling III, MD, LLC Past Accepting new patients

Locations

76 Summer St
Ste 210
Fitchburg, MA 01420
Phone (978) 343-9400

87 N Main St
Leominster, MA 01453
Phone (800) 688-6663

Interoperability endpoints

  • Direct secure messaging: holly.mazur@fmmc.eclinicaldirectplus.com
  • FHIR API: https://fhir4.healow.com/fhir/r4/HAJFCA

Organizations & group practices 2

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

Hospital & facility affiliations 5

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

NPI Registry JSON

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

{
    "created_epoch": "1148428800000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1789516800000",
    "number": "1295780617",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "321 MAIN ST",
            "city": "ACTON",
            "state": "MA",
            "postal_code": "017203799",
            "telephone_number": "978-635-8700"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "321 MAIN ST",
            "city": "ACTON",
            "state": "MA",
            "postal_code": "017203799",
            "telephone_number": "978-635-8700",
            "fax_number": "978-635-8923"
        }
    ],
    "practiceLocations": [],
    "basic": {
        "last_name": "MAZUR",
        "first_name": "HOLLY",
        "middle_name": "ANN",
        "credential": "M.D.",
        "sole_proprietor": "NO",
        "sex": "F",
        "enumeration_date": "2006-05-24",
        "last_updated": "2026-09-16",
        "certification_date": "2023-03-30",
        "deactivation_date": "2026-05-17",
        "reactivation_date": "2026-09-16",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "CT",
            "license": "61790",
            "primary": false
        },
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "MA",
            "license": "81939",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": [
        {
            "first_name": "HOLLY",
            "last_name": "ENTERLINE",
            "middle_name": "ANN",
            "credential": "MD",
            "code": "1",
            "type": "Former Name"
        }
    ]
}

Other providers in Acton, MA

Sources for this page

  • NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Sep 16, 2026; self-reported and not verified by CMS. Specialty names from the NUCC taxonomy.
  • 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.