Evaluation of preoperative computed tomography in gastric malignancy. Ninety patients with gastric malignancy underwent computed tomography (CT) before surgery. The CT findings regarding neoplastic invasion of adjacent organs and metastasis or enlarged lymph nodes were compared with the findings at laparotomy (85 cases) or autopsy (5 cases), thus permitting evaluation of the diagnostic accuracy of CT and its usefulness for predicting resectability. When present, neoplastic invasion of adjacent organs was overestimated or underestimated by CT in 21 cases. Invasion of adjacent organs according to CT was false positive in 17 cases and false negative in 11 cases. When liver metastasis or enlarged regional or distant lymph nodes were present, CT overestimated or underestimated their extent in 17 cases, and the diagnosis was false positive in one case and false negative in 33 cases. The positive and negative predictive values of CT concerning resectability of the tumor were 81% and 64%, respectively. Routine preoperative CT in gastric malignancy is concluded to be of limited value and surgical exploration, when feasible, remains the method of choice. 