Mark C O'Brien, D.O.

Primary specialty

Internal Medicine PhysicianTaxonomy code 207R00000X

License

20A6017 Issued in CA

Practice address

161 Thunder Dr Ste 210
Vista, CA 92083-6052

Phone

(760) 216-6500

Fax

(760) 295-4753

NPI assigned

Oct 14, 2005

Sex

Male

Sole proprietor

No

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

Specialties & licenses 1

Addresses

Medicare fee-for-service enrollment

Enrolled in CA

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

Internal Medicine

Education

Michigan State University College of Osteopathic Medicine, 1987

Medicare assignment

Accepts the Medicare-approved amount as payment in full

Telehealth

Offers telehealth services

Practice addresses (Care Compare)

Hospital & facility affiliations

• Tri-City Medical Center Hospital, Oceanside, CA, CCN 050128

Procedures performed for Medicare patients

Medicare enrollment (NPD)

Enrolled

Credentials

Doctor of Osteopathy

State licenses

Practice roles

Locations

Networks

• BSC 65 PLUS INDIVIDUAL MAPD

Interoperability endpoints

• Direct secure messaging: mark.o.brien.1@32337.direct.athenahealth.com

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.

• Mark C. O'Brien, D.O., Inc.

  • Internal Medicine Physician
  • Vista, CA
  • NPI 1346060860
  Medicare reassignment NPD Authorized official
• Hospitalist Medicine Physicians of California, Inc

  • Internal Medicine Physician
  • Apple Valley, CA
  • NPI 1184663965
  Medicare reassignment NPD
• Inpatient Specialists of California, PC

  • Internal Medicine Physician
  • San Bernardino, CA
  • NPI 1952792475
  Medicare reassignment NPD
• Kansal Inc

  • Internal Medicine Physician
  • West Hollywood, CA
  • NPI 1043510183
  Medicare reassignment NPD
• North County Health Project Inc

  • Federally Qualified Health Center (FQHC)
  • San Marcos, CA
  • NPI 1588489975
  NPD (past)

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

• Tri-City Hospital

  • General Acute Care Hospital
  • Oceanside, CA
  • NPI 1801861190
  Care Compare affiliation

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

{
    "created_epoch": "1129248000000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1743465600000",
    "number": "1497744247",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "161 THUNDER DR STE 210",
            "city": "VISTA",
            "state": "CA",
            "postal_code": "920836052",
            "telephone_number": "760-216-6500",
            "fax_number": "760-295-4753"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "161 THUNDER DR STE 210",
            "city": "VISTA",
            "state": "CA",
            "postal_code": "920836052",
            "telephone_number": "760-216-6500",
            "fax_number": "760-295-4753"
        }
    ],
    "practiceLocations": [],
    "basic": {
        "last_name": "O'BRIEN",
        "first_name": "MARK",
        "middle_name": "C",
        "credential": "D.O.",
        "sole_proprietor": "NO",
        "sex": "M",
        "enumeration_date": "2005-10-14",
        "last_updated": "2025-04-01",
        "certification_date": "2025-04-01",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207R00000X",
            "taxonomy_group": "",
            "desc": "Internal Medicine",
            "state": "CA",
            "license": "20A6017",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": []
}

• Laura Lynn Nunez
• Marline Berenice Nunez
• Kristen E Nurkowski, MSW, LCSW
• Cynthia Lynn Nutter, M.F.T.
• Mary Ann Nycum, MA MFT
• Paulette Louise O'Connor, DDS
• Diane Mary Oakes, M.A. MFT
• Oasis Medical Group
• Oasis Smiles Dentistry-Dr Sasha Bhor DDS Inc
• Alexandra Ochoa

• Internal Medicine Physician in Vista, CA
• Providers in Vista, CA by specialty
• Internal Medicine Physician in California

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Apr 1, 2025; 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.