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

Mark Stephen Singer, MD

Individual provider Emergency Medicine Physician · NPI 1962486332

Mark Stephen Singer, MD practises Internal Medicine in Napa, California. Graduated from University of California, Geffen School of Medicine in 1983, 43 years ago. Practices as a sole proprietor and accepts Medicare assignment. Licensed in California.

Years since qualifying
43
Trained at
University of California, Geffen School of Medicine
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

3334 Sterling Ct
Napa, CA 94558-4262 Not confirmed with CMS for 16 years — call before visiting
Phone: (707) 365-5151
Fax: (707) 252-4887
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence G53924 (CA)
Emergency Medicine Physician Taxonomy 207P00000X · Licence CAG539243 (CA)

Record details

NPI number1962486332
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedNovember 30, 2005
Last updated in NPPESJuly 12, 2010

Medicare enrollment

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

Medicare specialtyINTERNAL MEDICINE
Also practisesEMERGENCY MEDICINE
Medical schoolUNIVERSITY OF CALIFORNIA, GEFFEN SCHOOL OF MEDICINE
Graduated 1983 (43 years in practice)
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Removal of skin lesions 12 times · 59th percentile

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

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 patients200
Services billed 1,140 a service is one billed item, such as a visit, a test or a procedure
Average patient age85

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.

Other providers in Napa