The Illinois Radiological Society (IRS) is a Chapter of the American College of Radiology (ACR). Membership includes radiologists, radiation oncologists, medical physicists, interventional radiologists and nuclear medicine physicians.

The IRS is comprised of two divisions: the Chicago Radiological Society (CRS) covering Chicago and its suburbs; and the Central Illinois Radiological Society (CIRS) covering the rest of the state. Two thirds of IRS members and its leadership are in the CRS and one third are in the CIRS.