Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Jon Stephen Portnoff, MD

Individual provider Cardiovascular Disease Physician · NPI 1609874445

Jon Stephen Portnoff, MD is registered under Cardiovascular Disease (Cardiology) in Ukiah, California. Qualified in 1984, 42 years ago. Practices with Willits Hospital Inc, a 67-clinician group and accepts Medicare assignment. Licensed in California.

Years since qualifying
42
Licensed in
CA
In the registry since
2005
Specialties on file
2
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

260 Hospital Dr Ste 207
Ukiah, CA 95482-4533 Not confirmed with CMS for 14 years — call before visiting
Phone: (707) 463-2400
Fax: (707) 463-3520
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Cardiovascular Disease Physician (primary) Taxonomy 207RC0000X · Licence A43219 (CA)
Interventional Cardiology Physician Taxonomy 207RI0011X · Licence A43219 (CA)

Record details

NPI number1609874445
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedJuly 13, 2005
Last updated in NPPESOctober 25, 2012

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyCARDIOVASCULAR DISEASE (CARDIOLOGY)
Medical schoolOTHER
Graduated 1984 (42 years in practice)
Group practice Willits Hospital Inc — 67 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations6 on file with Medicare

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients1,039
Services billed 3,181 a service is one billed item, such as a visit, a test or a procedure
Average patient age77

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician. Those with a page here are linked.

Colleagues at Willits Hospital Inc

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 67 clinicians in the practice; 12 are shown here.

Other providers in Ukiah