CT potentialities in the diagnosis of diaphragmatic diseases were considered. CT provides valuable information in relaxations of the diaphragm and diaphragmitides, permitting the detection of infiltration of the diaphragm by a tumor, retroperitoneal fibrosis, diaphragmatic cysts, Bochdalek's hernia, and hernias of the esophageal opening. An algorithm for investigation of patients with suspected diaphragmatic pathological conditions was proposed.