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Healthcare Providers & Facilities in Ontario, CA

Public healthcare directory of 5,391 individual practitioners and 692 healthcare facilities located in Ontario, California.

5,391 Practitioners
692 Facilities
149 Specialties

Medical Specialties in Ontario

Select a specialty to view practitioner listings, practice locations, and qualifications.

Ask about interpreters and office accessibility

All Specialties in Ontario

Specialties with enough public records for a comparison with U.S. figures, besides those named above, plus the 60 largest of 142 more with at least one listed practitioner. Number of practitioners in brackets.

Chiropractic Providers

Dietary & Nutritional Service Providers

Eye and Vision Services Providers

Physician Assistants & Advanced Practice Nursing Providers

Podiatric Medicine & Surgery Service Providers

Speech, Language and Hearing Service Providers

Featured Healthcare Providers in Ontario

Practitioner profiles in Ontario, CA with recent CMS Medicare or Open Payments data.

Dr. Lan Dinh , DDS

Dentist

2920 S Archibald Ave, Ontario, CA
Phone: 9099232273
NPI 1114976347

Dr. Jacquelyn Dang , DO

Psychiatry & Neurology - Psychiatry

Medicare Accepted
2940 Inland Empire Blvd, Ontario, CA
Phone: 9094581350
NPI 1154778934

Cherilou Concepcion , NP

Nurse Practitioner - Family

Medicare Accepted
3333 Concours St, Ontario, CA
Phone: 9094764077
NPI 1679191951

Dr. Jose Ramirez , DDS

Dentist - General Practice

524 N Palm Ave, Ontario, CA
Phone: 9094672039
NPI 1003126343

Dr. Wayne Nakamura , DDS

Dentist - General Practice

2523 S Euclid Ave, Ontario, CA
Phone: 9099830908
NPI 1851430573

Mark Recio

Nurse Practitioner - Family

Medicare Accepted
3110 E Guasti Rd Ste 315, Ontario, CA
Phone: 3463761702
NPI 1215474390

Largest Cities in California

Other California cities with a full directory, by the number of active practitioners listed in NPPES.

How Ontario compares with the U.S.

Compared with the U.S. as a whole, Ontario has fewer clinicians in Family Medicine (31% of the U.S. rate), Nurse Practitioners (35%) and clinicians in Nurse Practitioner - Family (38%) per 100,000 residents.

Ontario has 2,986 active clinicians per 100,000 residents, compared with 2,198 for the U.S.

What these numbers mean

Clinicians per 100,000 residents compares places of different sizes. We count active clinicians who list a practice address in the area in the federal NPI registry (NPPES) and divide by the number of people who live there, according to the U.S. Census Bureau. The U.S. rate is the same calculation for the whole country.

A higher number does not mean it is easier to get an appointment, that wait times are shorter, or that care is better. It also does not show how many clinicians are accepting new patients or which insurance plans they take. A lower number does not by itself mean there is a shortage.

City counts use the city name in each clinician's practice address. That postal city can cover a larger or smaller area than the city limits the Census Bureau uses for population, and many clinicians list only one address even if they work in several places.

85% of clinicians in Ontario listed in the CMS Medicare file (162 of 191) accept Medicare assignment. That is lower than the California share of 91%.

Only 191 of 5,391 active clinicians in Ontario appear in the CMS Medicare file, so this share describes that smaller group.

What is Medicare assignment?

A clinician who accepts Medicare assignment agrees to take the Medicare-approved amount as full payment for services that Original Medicare covers. You usually still pay your deductible and coinsurance. This comes from the CMS Doctors and Clinicians file and applies to Original Medicare only. Medicare Advantage plans have their own provider networks. It does not show whether a clinician is taking new patients.

Some clinicians are listed as "may accept assignment," which means they can decide case by case. Clinicians without an assignment flag, or who are not in the CMS file, are not counted as accepting assignment. That does not mean they refuse Medicare. Ask the office before your visit.

12% of clinicians in Ontario listed in the CMS Medicare file (23 of 191) have a CMS telehealth indicator, meaning their recent Medicare claims include telehealth services. That is lower than the California share of 28%.

About the telehealth indicator

The telehealth indicator comes from CMS. It marks clinicians whose recent paid Medicare claims include services delivered by telehealth. It means a clinician has provided some services by telehealth, not that every visit can be done online. A clinician without the indicator may still offer telehealth, for example to patients who are not on Medicare. Ask the office which visits can be done by video or phone.

These figures summarize public federal data. They do not measure quality of care, appointment availability, or whether a clinician accepts your insurance or new patients. Registry addresses can be out of date. Please confirm details directly with the office and your plan. This information is not medical advice.

Prepared by T-MedInfo from NPPES, CMS and U.S. Census Bureau data. Questions or corrections: support@true-medinfo.com ยท Methodology

Sources: Clinician counts and practice addresses: NPPES NPI Registry, Centers for Medicare & Medicaid Services (CMS), data as of August 2026. Medicare assignment and telehealth indicators: CMS Doctors and Clinicians National Downloadable File. Population: U.S. Census Bureau, American Community Survey 2020-2024 5-Year Estimates, Table B01003 (Total Population).

Ontario CMS Healthcare & Financial Disclosures

CMS Part D Prescribers (2024), Open Payments (program year 2025), Medicare (PECOS) enrollment and Part B (2024) data for Ontario, CA

Source: CMS public datasets

Healthcare operations in Ontario, CA encompass 5,391 active individual practitioners and 692 registered medical facilities across 149 clinical specialties.

According to CMS Medicare Part D analytics for 2024, prescription drug volume in Ontario accounts for $10.9 Million across 142,630 prescription claims. 434 local practitioners have a Medicare (PECOS) enrollment record. Open Payments data for program year 2025 list $0.1 Million in payments reported by companies to 132 local practitioners; a reported payment does not necessarily mean the financial relationship is improper.

Medicare Part D Prescriptions (2024) $10.9M 142,630 Prescription Claims Source: data.cms.gov
Open Payments Sunshine Act (2025) $0.1M 132 Recipients Disclosed A reported payment does not necessarily mean the financial relationship is improper. Source: openpaymentsdata.cms.gov
Medicare (PECOS) Enrollment 434 Enrolled Medicare Practitioners Source: data.cms.gov
Medicare Part B Allowed Volume (2024) $20.3M 171,023 Services Performed Source: data.cms.gov

CMS PECOS: Eligible to Order or Refer for Medicare in Ontario

Part B Lab & Imaging Eligible: 319
Durable Medical Equipment (DME): 337
Home Health Agency (HHA): 210
Source: CMS Order and Referring