Quick answers
- Which hospitals does John T. O'Brien work at?
- Medicare's official clinician data lists John T. O'Brien at 1 hospital: Inova Fairfax Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does John T. O'Brien see patients?
- Medicare's clinician data lists 4 practice locations, including Falls Church, VA, Arlington, VA and Annandale, VA. Call before your visit to confirm the address.
- What is John T. O'Brien's specialty?
- Medicare lists Cardiovascular Disease (Cardiology) as the primary specialty, and also Internal Medicine.
- Does John T. O'Brien accept Medicare assignment?
- Yes. Medicare's clinician data says John T. O'Brien accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for John T. O'Brien?
- (703) 256-5680, as listed in official Medicare / NPI Registry data.
- What is John T. O'Brien's NPI number?
- 1952392482. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where John T. O'Brien works
Medicare's Facility Affiliation Data lists John T. O'Brien at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Inova Fairfax HospitalFalls Church, VA · Acute Care Hospital · CCN 490063
Practice locations
Addresses where John T. O'Brien is enrolled with Medicare (CMS data updated 2026-10-02).
- 3300 Gallows RdFalls Church, VA 22042
- 3833 Fairfax DrArlington, VA 22203
- 7619 Little River Tpke, Suite 1000Annandale, VA 22003 (703) 256‑5680
- 8081 Innovation Park DrFairfax, VA 22031
Group practices
Medicare enrollment lists John T. O'Brien as a member of this group (CMS data updated 2026-10-02).
- Inova Health Care Services1,817 clinicians in the group
Specialties
Find other Cardiovascular Disease (Cardiology) doctors in Virginia →
Other cardiologists in Falls Church
Clinicians with the same Medicare primary specialty in Falls Church, VA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Georgetown University School Of Medicine |
| Graduation year | 1977 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1952392482 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians