In a prospective study from November 1989 to December 1993, the accuracy of computed tomography (CT), endoscopic ultrasonography (EUS) and intraoperative surgical assessment were compared for the evaluation of the depth of invasion (T category) and involvement of lymph nodes (N category) in patients with gastric carcinoma. Sixty-nine consecutive patients who received preoperative CT and EUS underwent subsequent surgery. CT and EUS results were compared with histopathologic staging of tumor invasion depth and regional lymph node metastasis (pT and pN categories). T categories were staged correctly in 42% of the cases by CT, 71% by EUS and 55% by intraoperative surgical assessment. CT correctly staged 49% of N1 and N2 lymph nodes compared with 65% for EUS and 45% for intraoperative surgical assessment. CT was more accurate for advanced cancer but had a tendency to understage the T and N categories. EUS was more accurate for serosal cancer and displayed a tendency to overstage T categories and understage N categories. Intraoperative surgical assessment overstaged early T stages, understaged the T4 stage and had a tendency to overstage N categories. CT and intraoperative surgical assessment of T and N categories were of limited value in the staging of gastric carcinoma compared to EUS. EUS is a valuable form of assessment to evaluate gastric cancer staging before surgery.