Quick answers
- Where does Ruben Ruiz see patients?
- Medicare's clinician data lists 3 practice locations, including Ontario, CA, Rialto, CA and Montebello, CA. Call before your visit to confirm the address.
- What is Ruben Ruiz's specialty?
- Medicare lists Internal Medicine as the primary specialty.
- Does Ruben Ruiz accept Medicare assignment?
- Medicare's clinician data says Ruben Ruiz may accept Medicare assignment (as of 2026-10-02). Ask the office whether they accept it for your visit.
- What is the phone number for Ruben Ruiz?
- (909) 988-3288, as listed in official Medicare / NPI Registry data.
- What is Ruben Ruiz's NPI number?
- 1912901471. 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 Ruben Ruiz is enrolled with Medicare (CMS data updated 2026-10-02).
- 403 W F StOntario, CA 91762 (909) 988‑3288
- 436 S Riverside AveRialto, CA 92376 (909) 877‑8668
- 833 W Whittier BlvdMontebello, CA 90640 (323) 712‑4811
Group practices
Medicare enrollment lists Ruben Ruiz as a member of these groups (CMS data updated 2026-10-02).
- R. Ruiz MD a Professional Corporation3 clinicians in the group
- Ruben Ruiz M D A Medical Corporation2 clinicians in the group
Specialties
- Internal Medicineprimary
Other internal medicine doctors in Ontario
Clinicians with the same Medicare primary specialty in Ontario, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of California, Geffen School Of Medicine |
| Graduation year | 1982 |
| Gender (as listed) | Male |
| Medicare assignment | May accept for some services |
| NPI (National Provider Identifier) | 1912901471 |
| 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