John Charles Michalak, M.D.

Primary specialty

Hematology & Oncology PhysicianTaxonomy code 207RH0003X

License

21969 Issued in IA

Practice address

230 Nebraska St
Sioux City, IA 51101-1733

Phone

(712) 252-0088

Fax

(712) 252-5271

NPI assigned

Feb 2, 2006

Sex

Male

Sole proprietor

No

Registry information is reported by the provider to CMS and is not verified. About this source

Specialties & licenses 1

Addresses

Other identifiers 1

Medicare fee-for-service enrollment

Not listed in the public Medicare enrollment file

Medicare enrollment (NPD)

Enrolled

Credentials

Doctor of Medicine

State licenses

Practice roles

Organizations this provider is connected to: Medicare benefit reassignments (the organization bills Medicare for this provider’s services), Care Compare group memberships and National Provider Directory roles.

• Siouxland Hematology Oncology Associates LLP

  • Hematology & Oncology Physician
  • Sioux City, IA
  • NPI 1811914575
  NPD (past)

The complete NPPES record for this NPI in the NPI Registry API format.

{
    "created_epoch": "1138838400000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1783900800000",
    "number": "1497727663",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "230 NEBRASKA ST",
            "city": "SIOUX CITY",
            "state": "IA",
            "postal_code": "511011733",
            "telephone_number": "712-252-0088",
            "fax_number": "712-252-5271"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "230 NEBRASKA ST",
            "city": "SIOUX CITY",
            "state": "IA",
            "postal_code": "511011733",
            "telephone_number": "712-252-0088",
            "fax_number": "712-252-5271"
        }
    ],
    "practiceLocations": [],
    "basic": {
        "last_name": "MICHALAK",
        "first_name": "JOHN",
        "middle_name": "CHARLES",
        "credential": "M.D.",
        "sole_proprietor": "NO",
        "sex": "M",
        "enumeration_date": "2006-02-02",
        "last_updated": "2026-07-13",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207RH0003X",
            "taxonomy_group": "",
            "desc": "Internal Medicine, Hematology & Oncology",
            "state": "IA",
            "license": "21969",
            "primary": true
        }
    ],
    "identifiers": [
        {
            "code": "05",
            "desc": "MEDICAID",
            "issuer": null,
            "identifier": "0171322",
            "state": "IA"
        }
    ],
    "endpoints": [],
    "other_names": []
}

• Clifford J Meylor, DC
• MHC Anesthesia Services
• MHC Child Protection
• Michael P Baker Dba Associates for Psycholoigcal & Therapy Services
• Michael Wadzinski, PC (Wadzinski Eye Clinic PC)
• Mid Step Services
• Mid-Step Services, Inc. (Park View Homes)
• Mid-Step Services, Inc. (Courage Homes)
• Mid-Step Services, Inc. (HCBS Waiver)
• Lorayne Caroline Middendorp, OD

• Hematology & Oncology Physician in Sioux City, IA
• Providers in Sioux City, IA by specialty
• Hematology & Oncology Physician in Iowa

• NPPES NPI Registry (CMS): identity, addresses, specialties, licenses, identifiers and endpoints. Last updated by the provider on Jul 13, 2026; self-reported and not verified by CMS. Specialty names from the NUCC taxonomy.
• National Provider Directory (CMS): practice roles, locations, licenses, networks and endpoints.

Verify at the official NPI Registry.