Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Mark Ratain

Individual provider Medical Oncology Physician · NPI 1255494779

Mark Ratain practises Medical Oncology in Chicago, Illinois. Graduated from Yale University School of Medicine in 1980, 46 years ago. Practices with The University of Chicago Medical Center, a 909-clinician group, accepts Medicare assignment and offers telehealth. Licensed in Illinois.

Years since qualifying
46
Trained at
Yale University School of Medicine
Licensed in
IL
In the registry since
2006
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Practice location Address checks out

5841 S Maryland Ave
Chicago, IL 60637-1443
Phone: (888) 824-0200
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Medical Oncology Physician (primary) Taxonomy 207RX0202X · Licence 036066554 (IL)

Record details

NPI number1255494779
Entity typeIndividual (Type 1)
GenderMale
Sole proprietorNo
NPI enumeratedDecember 18, 2006
Last updated in NPPESJune 9, 2026
Certification dateJune 9, 2026

Medicare enrollment

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

Medicare specialtyMEDICAL ONCOLOGY
Medical schoolYALE UNIVERSITY SCHOOL OF MEDICINE
Graduated 1980 (46 years in practice)
Group practice The University Of Chicago Medical Center — 909 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations2 on file with Medicare

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients90
Services billed 102 a service is one billed item, such as a visit, a test or a procedure
Average patient age69

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at The University of Chicago Medical Center

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 909 clinicians in the practice; 12 are shown here.

Other providers in Chicago