Quick answers
- Where does Marshall S. Horwitz see patients?
- Medicare's clinician data lists 1 practice location in Seattle, WA. Call before your visit to confirm the address.
- What is Marshall S. Horwitz's specialty?
- Medicare lists Medical Genetics and Genomics as the primary specialty.
- Does Marshall S. Horwitz accept Medicare assignment?
- Yes. Medicare's clinician data says Marshall S. Horwitz 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 Marshall S. Horwitz?
- (206) 598-4333, as listed in official Medicare / NPI Registry data.
- What is Marshall S. Horwitz's NPI number?
- 1013007970. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where Marshall S. Horwitz is enrolled with Medicare (CMS data updated 2026-10-02).
- 1959 NE Pacific StSeattle, WA 98195 (206) 598‑4333
Group practices
Medicare enrollment lists Marshall S. Horwitz as a member of this group (CMS data updated 2026-10-02).
- The Association of University Physicians3,535 clinicians in the group
Specialties
Find other Medical Genetics and Genomics doctors in Washington →
Other medical geneticists in Seattle
Clinicians with the same Medicare primary specialty in Seattle, WA — not a recommendation.
Clinician information
| Medical school | University Of Washington School Of Medicine |
|---|---|
| Graduation year | 1990 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1013007970 |
| 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
- 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