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

William J O'Brien, MD

Individual provider Surgery Physician · NPI 1831101955

William J O'Brien, MD practises General Surgery in Aurora, Illinois. Graduated from University of Wisconsin School of Medicine in 1989, 37 years ago. Practices with Advocate Health and Hospitals Corporation, a 3,079-clinician group and accepts Medicare assignment. Licensed in Illinois.

Years since qualifying
37
Trained at
University of Wisconsin School of Medicine
Licensed in
IL
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

1221 N Highland Ave
Aurora, IL 60506-1404
Phone: (630) 859-8700
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Surgery Physician (primary) Taxonomy 208600000X · Licence 036-092894 (IL)

Record details

NPI number1831101955
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedAugust 13, 2006
Last updated in NPPESNovember 18, 2021
Certification dateNovember 18, 2021

Medicare enrollment

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

Medicare specialtyGENERAL SURGERY
Medical schoolUNIVERSITY OF WISCONSIN SCHOOL OF MEDICINE
Graduated 1989 (37 years in practice)
Group practice Advocate Health And Hospitals Corporation — 3079 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Hernia repair - groin (open) 16 times · 94th percentile
Melanoma (skin cancer) excision 70 times · 90th percentile
Hernia repair (minimally invasive) 1–10 times
Removal of skin lesions 1–10 times
Removal of tissue 1–10 times
Varicose vein removal 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

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 patients517
Services billed 853 a service is one billed item, such as a visit, a test or a procedure
Average patient age76

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 Advocate Health and Hospitals Corporation

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 3079 clinicians in the practice; 12 are shown here.

Other providers in Aurora