Quick answers
- Which hospitals does Mary M. O'Neil work at?
- Medicare's official clinician data lists Mary M. O'Neil at 5 hospitals: Brooks-Tlc Hospital System, Inc, Kaleida Health, Mercy Hospital of Buffalo, Sisters of Charity Hospital and UPMC Chautauqua at Wca. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mary M. O'Neil see patients?
- Medicare's clinician data lists 3 practice locations, including Cheektowaga, NY and Williamsville, NY. Call before your visit to confirm the address.
- What is Mary M. O'Neil's specialty?
- Medicare lists Rheumatology as the primary specialty.
- Does Mary M. O'Neil accept Medicare assignment?
- Yes. Medicare's clinician data says Mary M. O'Neil 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.
- Does Mary M. O'Neil offer telehealth?
- Medicare's clinician data says Mary M. O'Neil offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Mary M. O'Neil?
- (716) 898-0755, as listed in official Medicare / NPI Registry data.
- What is Mary M. O'Neil's NPI number?
- 1598790818. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Mary M. O'Neil works
Medicare's Facility Affiliation Data lists Mary M. O'Neil at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Brooks-Tlc Hospital System, IncDunkirk, NY · Acute Care Hospital · CCN 330229
- Kaleida HealthBuffalo, NY · Acute Care Hospital · CCN 330005
- Mercy Hospital of BuffaloBuffalo, NY · Acute Care Hospital · CCN 330279
- Sisters of Charity HospitalBuffalo, NY · Acute Care Hospital · CCN 330078
- UPMC Chautauqua at WcaJamestown, NY · Acute Care Hospital · CCN 330239
Practice locations
Addresses where Mary M. O'Neil is enrolled with Medicare (CMS data updated 2026-10-02).
- 2355 Union Rd, Suite 100Cheektowaga, NY 14227 (716) 898‑0755
- 2507 Harlem RdCheektowaga, NY 14225 (716) 893‑4797
- 400 International DrWilliamsville, NY 14221 (716) 631‑3555
Group practices
Medicare enrollment lists Mary M. O'Neil as a member of these groups (CMS data updated 2026-10-02).
- Brain and Spine Medical Services PLLC56 clinicians in the group
- Rheumatology Wellness Care of Wny PLLC4 clinicians in the group
Specialties
- Rheumatologyprimary
Other rheumatologists in New York
Clinicians with the same Medicare primary specialty in New York — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Saint Louis University School Of Medicine |
| Graduation year | 1990 |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1598790818 |
| 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