We observed the quantitative estimation of the transmural changes associated with gastric ulcer healing by using endoscopic ultrasonography (EUS). It was possible to diagnose the depth of ulcer by EUS. Forty-eight patients were divided into three treatment groups. Group A (n = 16) was treated with 800 mg cimetidine daily, group B (n = 22) with 20 mg omeprazole daily, and group C (n = 10) with 400 mg cimetidine + 300 mg gefarnate daily. EUS was performed before and after 2, 4, and 8 weeks of treatment. The groups were compared from the viewpoints of endoscopic findings and contraction rate of the length and the cross-sectional area of the ulcer in EUS pictures. The best healing of both the endoscopic and EUS findings was seen in group B. By estimating the changes inside the ulcer, EUS may provide useful information for choice of anti-ulcer agents.