Prospectively, 72 patients with a gastric carcinoma were studied endosonographically before surgery. The results were correlated with those obtained with the histology of resected specimens according to the new (1987) TNM classification. Endoscopic ultrasonography (EUS) was accurate in assessing the extent and depth of tumor infiltration. Early gastric carcinoma could readily be distinguished from advanced carcinoma. The overall accuracy of EUS was 84.7%. Occasionally, overstaging and understaging occurred. Stenosis was a factor limiting accurate staging. EUS was reasonably accurate in the assessment of lymph node metastasis. The overall accuracy was 81.0%. In non-metastatic lymph nodes, however, the accuracy was only 50%. Difficulties occurred in distinguishing granulomatous lymph nodes and small micrometastatic lymph node involvement. EUS was not accurate in diagnosing distant metastasis, due to the limited depth of penetration of ultrasound. Technical improvements such as a reduction in the diameter of the echoprobe, and the use of the biopsy channel for EUS-guided cytological puncture will further enhance the accuracy of EUS.