The preoperative use of endoscopic ultrasound was evaluated in 74 patients with confirmed gastric cancer. It was used in diagnosing the depth of invasion in the gastric wall, the infiltration to the adjacent organs, and the involvement of the perigastric lymph nodes. Results were compared with histological findings in resected specimens. Accuracy in staging gastric cancer using the T grade of the 1987 TNM system was 81.1% (60 of 74 patients). Endoscopic ultrasound provided excellent results compared with computed tomography and conventional ultrasound, particularly in evaluating perigastric lymph node metastasis and direct infiltration to the adjacent organs. The success rate in detecting lymph node metastasis was 50% (11 of 22 patients); the accuracy in diagnosing direct infiltration to the adjacent organs was 60% (three of five patients). This technique is useful in diagnosing malignant invasion and lymph node metastasis of gastric carcinomas but requires further refinement for use in diagnosing the disease itself. Its preoperative use is recommended for establishing surgical and other treatment plans, as well as in predicting the prognosis of gastric cancer.