Recently Updated NPI Information — some details in this NPI profile have been updated in the NPI registry within the last 30 days.

JOHN CHARLES MICHALAK M.D.
NPI 1497727663
Internal Medicine - Hematology & Oncology in Sioux City, IA

Q: What is John Michalak's NPI number?

The NPI number for John Michalak is 1497727663. It was assigned to this individual provider in the NPPES registry on February 2, 2006.

Q: What is John Michalak's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Hematology & Oncology, with taxonomy code 207RH0003X.

Q: When was this NPI record last updated?

The NPPES record for John Michalak was last updated on July 13, 2026. NPI Profile syncs with the weekly NPPES data releases published by CMS.

Active since February 02, 2006

230 NEBRASKA ST, SIOUX CITY, IA 51101(712) 252-0088(712) 252-5271 Get Directions Write a Review

NPPES record last updated: July 13, 2026. Verified against the NPPES registry weekly; last sync: July 19, 2026.

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About John Charles Michalak M.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

JOHN CHARLES MICHALAK M.D. (NPI 1497727663) is an individual hematology & oncology provider in Sioux City, Iowa, licensed in Iowa (21969) and active in the NPI registry since February 2006.

NPPES Registry Identity

NPI1497727663

Entity TypeIndividualMale

Primary Taxonomy207RH0003X

Provider Legal NameJOHN CHARLES MICHALAKCredential: M.D.

Location Address230 NEBRASKA STSioux City, IA 51101-1733

Mailing Address230 Nebraska StSioux City, IA 51101-1733 · (712) 252-0088 · Fax (712) 252-5271

Phone(712) 252-0088

Fax(712) 252-5271

Sole ProprietorNo

Enumeration DateFebruary 2, 2006

Last NPPES UpdateJuly 13, 2026

✔ NPI 1497727663 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal Medicine · Hematology & OncologyAllopathic & Osteopathic Physicians

Taxonomy Code207RH0003X

License✔ Licensed in IA · 21969

Definition

An internist doctor of osteopathy that specializes in the treatment of the combination of hematology and oncology disorders. A doctor of osteopathy that is board eligible/certified by the American Osteopathic Board of Internal Medicine WAS able to obtain a Certificate of Special Qualifications in the field of Hematology and Oncology. The Certificate is NO longer offered.

230 NEBRASKA ST, Sioux City, IA 51101

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