Quick answers
- Which hospitals does Brett J. Halloran work at?
- Medicare's official clinician data lists Brett J. Halloran at 5 hospitals: Adventist Health Clearlake, Adventist Health Howard Memorial, Adventist Health Mendocino Coast, Adventist Health St Helena and Adventist Health Ukiah Valley. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Brett J. Halloran see patients?
- Medicare's clinician data lists 6 practice locations, including Willits, CA, Saint Helena, CA and Victorville, CA. Call before your visit to confirm the address.
- What is Brett J. Halloran's specialty?
- Medicare lists Internal Medicine as the primary specialty, and also Hospitalist.
- Does Brett J. Halloran accept Medicare assignment?
- Yes. Medicare's clinician data says Brett J. Halloran 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 Brett J. Halloran?
- (707) 459-6801, as listed in official Medicare / NPI Registry data.
- What is Brett J. Halloran's NPI number?
- 1235280470. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Brett J. Halloran works
Medicare's Facility Affiliation Data lists Brett J. Halloran at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Adventist Health ClearlakeClearlake, CA · Critical Access Hospital · CCN 051317
- Adventist Health Howard MemorialWillits, CA · Critical Access Hospital · CCN 051310
- Adventist Health Mendocino CoastFort Bragg, CA · Critical Access Hospital · CCN 051325
- Adventist Health St HelenaSaint Helena, CA · Acute Care Hospital · CCN 050013
- Adventist Health Ukiah ValleyUkiah, CA · Acute Care Hospital · CCN 050301
Practice locations
Addresses where Brett J. Halloran is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 6; the Medicare profile lists all.
- 1 Marcela DrWillits, CA 95490 (707) 459‑6801
- 10 Woodland RdSaint Helena, CA 94574 (707) 963‑3611
- 15248 11th StVictorville, CA 92395 (760) 245‑8691
- 275 Hospital DrUkiah, CA 95482 (707) 462‑3111
- 700 River DrFort Bragg, CA 95437 (707) 961‑1234
Group practices
Medicare enrollment lists Brett J. Halloran as a member of this group (CMS data updated 2026-10-02).
- Galen Inpatient Physicians PC1,077 clinicians in the group
Specialties
- Internal Medicineprimary
- Hospitalistalso
Other internal medicine doctors in Willits
Clinicians with the same Medicare primary specialty in Willits, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2003 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1235280470 |
| 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