To evaluate the patterns of mesenteric disease as visualized by computed tomography (CT), we reviewed the scans of 370 patients whose primary diagnoses coincided with diseases known from the pathology literature to have frequent mesenteric involvement. Diagnoses included selected malignancies, inflammatory diseases, and traumatic injuries. Four general patterns of involvement of the mesentery were recognized: (a) rounded masses, (b) "cake-like" masses, (c) ill-defined masses, and (d) stellate mesentery. Of the malignancies reviewed, mesenteric involvement as visualized by CT occurred most commonly with ovarian carcinoma (20/52) and non-Hodgkin's lymphoma (41/134). The incidences of CT evidence of involvement of the mesentery with other common malignancies were carcinoma of the colon (8/68), carcinoma of the pancreas (5/21), and leukemia (5/19). Certain benign and malignant lesions of the mesentery do demonstrate unique CT patterns of involvement. Examples of the individual patterns in common and unusual disease states are illustrated.