We studied, the rate and the affecting factor of ulcer healing of patients with gastric body ulcer treated by H2-receptor antagonist (H2-RA) and proton pump inhibitor (PPI). Gastric acidity was also examined using 24 hr pH monitoring. No difference was observed between the affecting factor of ulcer healing and healing rate (94.7% and 94.9%) among the patients treated by H2-RA or PPI. The average time below pH3 during treatment with H2-RA or PPI were 17.4 +/- 4.3 hr and 23.0 +/- 1.5 hr, respectively. Acid suppression was superior in PPI treated group than in H2-RA group. From these findings, we concluded that H2-RA had sufficient therapeutic efficacy in treating gastric body ulcer.