Quick answers
- Which hospitals does Warren D. Johnston work at?
- Medicare's official clinician data lists Warren D. Johnston at 1 hospital: Providence St. Joseph Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Warren D. Johnston see patients?
- Medicare's clinician data lists 5 practice locations, including Orange, CA, Fullerton, CA and Anaheim, CA. Call before your visit to confirm the address.
- What is Warren D. Johnston's specialty?
- Medicare lists Cardiovascular Disease (Cardiology) as the primary specialty.
- Does Warren D. Johnston accept Medicare assignment?
- Yes. Medicare's clinician data says Warren D. Johnston 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 Warren D. Johnston offer telehealth?
- Medicare's clinician data says Warren D. Johnston offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Warren D. Johnston?
- (714) 633-9111, as listed in official Medicare / NPI Registry data.
- What is Warren D. Johnston's NPI number?
- 1427052802. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Warren D. Johnston works
Medicare's Facility Affiliation Data lists Warren D. Johnston at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Providence St. Joseph HospitalOrange, CA · Acute Care Hospital · CCN 050069
Practice locations
Addresses where Warren D. Johnston is enrolled with Medicare (CMS data updated 2026-10-02).
- 1100 W Stewart DrOrange, CA 92868 (714) 633‑9111
- 1140 W La Veta Ave, Suite 430Orange, CA 92868 (714) 543‑5555
- 1140 W La Veta Ave, Suite 770Orange, CA 92868 (714) 835‑8715
- 1950 Sunny Crest Dr, Suite 2900Fullerton, CA 92835 (714) 992‑5350
- 8078 E Santa Ana Canyon RdAnaheim, CA 92808 (714) 974‑2900
Group practices
Medicare enrollment lists Warren D. Johnston as a member of this group (CMS data updated 2026-10-02).
- Providence Medical Foundation1,466 clinicians in the group
Specialties
Find other Cardiovascular Disease (Cardiology) doctors in California →
Other cardiologists in Orange
Clinicians with the same Medicare primary specialty in Orange, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Rochester School Of Medicine And Dentistry |
| Graduation year | 1975 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1427052802 |
| 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