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

Dr. Mark Alan Klaas, MD

Individual provider Internal Medicine Physician · NPI 1215994298

Dr. Mark Alan Klaas, MD is an Internal Medicine Physician in Waukesha, Wisconsin. Practices as a sole proprietor. Licensed in Wisconsin.

Licensed in
WI
In the registry since
2006
Specialties on file
3
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

725 American Ave
Waukesha, WI 53188-5031
Phone: (262) 928-2391
Fax: (262) 928-2718
Show map & directions

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

Specialties & licences

Pulmonary Disease Physician (primary) Taxonomy 207RP1001X · Licence 31805 (WI)
Internal Medicine Physician Taxonomy 207R00000X · Licence 31805 (WI)
Critical Care Medicine (Internal Medicine) Physician Taxonomy 207RC0200X · Licence 31805 (WI)

Record details

NPI number1215994298
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedApril 26, 2006
Last updated in NPPESNovember 20, 2009
Mailing addressSouth 36 West 35541 Hwy D, Dousman, WI 53118

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