Quick answers
- Which hospitals does Mark K. Youssef work at?
- Medicare's official clinician data lists Mark K. Youssef at 2 hospitals: Griffin Hospital and Saint Mary's Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mark K. Youssef see patients?
- Medicare's clinician data lists 4 practice locations, including Waterbury, CT, Prospect, CT and Southbury, CT. Call before your visit to confirm the address.
- What is Mark K. Youssef's specialty?
- Medicare lists Diagnostic Radiology as the primary specialty, and also Interventional Radiology.
- Does Mark K. Youssef accept Medicare assignment?
- Yes. Medicare's clinician data says Mark K. Youssef 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 Mark K. Youssef?
- (203) 574-1311, as listed in official Medicare / NPI Registry data.
- What is Mark K. Youssef's NPI number?
- 1679910301. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Mark K. Youssef works
Medicare's Facility Affiliation Data lists Mark K. Youssef at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Griffin HospitalDerby, CT · Acute Care Hospital · CCN 070031
- Saint Mary's HospitalWaterbury, CT · Acute Care Hospital · CCN 070016
Practice locations
Addresses where Mark K. Youssef is enrolled with Medicare (CMS data updated 2026-10-02).
- 1389 W Main StWaterbury, CT 06708 (203) 574‑1311
- 166 Waterbury RdProspect, CT 06712 (203) 758‑7700
- 385 Main St SSouthbury, CT 06488 (203) 264‑7999
- 385 Main St S, Bldg 1Southbury, CT 06488 (203) 267‑5114
Group practices
Medicare enrollment lists Mark K. Youssef as a member of these groups (CMS data updated 2026-10-02).
- Naugatuck Valley Radiological Associates PC12 clinicians in the group
- Diagnostic Imaging of Southbury11 clinicians in the group
- Diagnostic Imaging Associates LLC10 clinicians in the group
- Prospect Diagnostic Imaging10 clinicians in the group
Specialties
- Diagnostic Radiologyprimary
- Interventional Radiologyalso
Other radiologists in Waterbury
Clinicians with the same Medicare primary specialty in Waterbury, CT — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2013 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1679910301 |
| 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