Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Dr. Man-Siak Mak, MD

Individual provider Gastroenterology Physician · NPI 1609875004

Dr. Man-Siak Mak, MD is a Gastroenterology in Merced, California. Qualified in 1968, 58 years ago. Practices with Timothy S Johnston MD PC, a 9-clinician group and accepts Medicare assignment. Licensed in California.

Years since qualifying
58
Licensed in
CA
In the registry since
2005
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

3349 G St Ste F
Merced, CA 95340
Phone: (209) 349-8459
Fax: (209) 580-4138
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Gastroenterology Physician (primary) Taxonomy 207RG0100X · Licence A26785 (CA)

Record details

NPI number1609875004
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedJuly 18, 2005
Last updated in NPPESApril 17, 2019

Medicare enrollment

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

Medicare specialtyGASTROENTEROLOGY
Also practisesINTERNAL MEDICINE
Medical schoolOTHER
Graduated 1968 (58 years in practice)
Group practice Timothy S Johnston Md Pc — 9 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

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