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

Dr. Dirk Ross Diefendorf, MD

Individual provider Sports Medicine (Neuromusculoskeletal Medicine) Physician · NPI 1467559443

Dr. Dirk Ross Diefendorf, MD is an Orthopedic Surgery in San Mateo, California. Graduated from Northwestern University Feinberg Medical School in 1983, 43 years ago. Practices as a sole proprietor and accepts Medicare assignment. Licensed in California.

Years since qualifying
43
Trained at
Northwestern University Feinberg Medical School
Licensed in
CA
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

See every abbreviation used in this directory →

Practice location Address checks out

101 S Ellsworth Ave Ste 607
San Mateo, CA 94401-3956
Phone: (650) 347-0157
Fax: (650) 347-0566
Show map & directions

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

Specialties & licences

Sports Medicine (Neuromusculoskeletal Medicine) Physician (primary) Taxonomy 204C00000X · Licence G53558 (CA)

Record details

NPI number1467559443
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedSeptember 20, 2006
Last updated in NPPESAugust 30, 2010

Medicare enrollment

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

Medicare specialtyORTHOPEDIC SURGERY
Medical schoolNORTHWESTERN UNIVERSITY FEINBERG MEDICAL SCHOOL
Graduated 1983 (43 years in practice)
Accepts Medicare assignment Yes — accepts the Medicare-approved amount