Quick answers
- Which hospitals does William C. Hillmann work at?
- Medicare's official clinician data lists William C. Hillmann at 1 hospital: Massachusetts General Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does William C. Hillmann see patients?
- Medicare's clinician data lists 1 practice location in Boston, MA. Call before your visit to confirm the address.
- What is William C. Hillmann's specialty?
- Medicare lists Hospitalist as the primary specialty, and also Internal Medicine.
- Does William C. Hillmann accept Medicare assignment?
- Yes. Medicare's clinician data says William C. Hillmann 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 William C. Hillmann?
- (617) 724-0287, as listed in official Medicare / NPI Registry data.
- What is William C. Hillmann's NPI number?
- 1669819892. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where William C. Hillmann works
Medicare's Facility Affiliation Data lists William C. Hillmann at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Massachusetts General HospitalBoston, MA · Acute Care Hospital · CCN 220071
Practice locations
Addresses where William C. Hillmann is enrolled with Medicare (CMS data updated 2026-10-02).
- 55 Fruit StBoston, MA 02114 (617) 724‑0287
Group practices
Medicare enrollment lists William C. Hillmann as a member of this group (CMS data updated 2026-10-02).
- Massachusetts General Physicians Organization Inc3,558 clinicians in the group
Specialties
- Hospitalistprimary
- Internal Medicinealso
Other hospitalists in Boston
Clinicians with the same Medicare primary specialty in Boston, MA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Tufts University School Of Medicine |
| Graduation year | 2013 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1669819892 |
| 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