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

Dr. Frederick Richard Stack, MD

Individual provider Internal Medicine Physician · NPI 1548256977

Dr. Frederick Richard Stack, MD is an Internal Medicine in Sioux City, Iowa. Graduated from University of Nebraska College of Medicine in 1991, 35 years ago. Practices with Benefis Hospitals Inc, a 398-clinician group, works from 4 locations and accepts Medicare assignment. Licensed in Arizona, Iowa and Montana.

Years since qualifying
35
Trained at
University of Nebraska College of Medicine
Licensed in
AZ, IA, MT
In the registry since
2005
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

801 5th St
Sioux City, IA 51101-1326
Phone: (712) 279-2010
Fax: (712) 279-2034
Show map & directions

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

Additional practice locations (3)

  • 1821 N Trekell Rd, Casa Grande, AZ 85222-1705 — (520) 421-1122
  • 1 Medical Center Dr, Biddeford, ME 04005-9422 — (207) 283-7937
  • 1101 26th St S, Great Falls, MT 59405-5161 — (406) 455-4694

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence MD-46368 (IA)
Internal Medicine Physician Taxonomy 207R00000X · Licence 91977 (MT)
Specialist Taxonomy 174400000X · Licence 24459 (AZ)

Record details

NPI number1548256977
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedSeptember 21, 2005
Last updated in NPPESJanuary 28, 2026
Certification dateJanuary 28, 2026
Mailing address6909 East Ray Road #15-114, Chandler, AZ 85226

Medicare enrollment

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

Medicare specialtyINTERNAL MEDICINE
Medical schoolUNIVERSITY OF NEBRASKA COLLEGE OF MEDICINE
Graduated 1991 (35 years in practice)
Group practice Benefis Hospitals Inc — 398 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations3 on file with Medicare

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