Quick answers
- Where does Fred J. Vonstieff see patients?
- Medicare's clinician data lists 1 practice location in Concord, CA. Call before your visit to confirm the address.
- What is Fred J. Vonstieff's specialty?
- Medicare lists Addiction Medicine as the primary specialty, and also Internal Medicine.
- Does Fred J. Vonstieff accept Medicare assignment?
- Yes. Medicare's clinician data says Fred J. Vonstieff 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 Fred J. Vonstieff?
- (925) 680-8933, as listed in official Medicare / NPI Registry data.
- What is Fred J. Vonstieff's NPI number?
- 1790849685. 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 Fred J. Vonstieff is enrolled with Medicare (CMS data updated 2026-10-02).
- 2481 Pacheco StConcord, CA 94520 (925) 680‑8933
Group practices
Medicare enrollment lists Fred J. Vonstieff as a member of this group (CMS data updated 2026-10-02).
- Fred J Von Stieff MD a Professional Corporation3 clinicians in the group
Specialties
- Addiction Medicineprimary
- Internal Medicinealso
Other addiction medicine doctors in California
Clinicians with the same Medicare primary specialty in California — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Un Of California, Irvine, College Of Medicine |
| Graduation year | 1976 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1790849685 |
| 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