Background:Argon plasma coagulation(APC) is a new method of contactfree electrocoagulation in which energy is transmitted to tissue through ionized argon gas. APC was effective and relatively safe in treating a wide range of G-I tract diseases. There are however few reports on the effect for endoscopic treatment of peptic ulcer bleeding. Aim:To evaluate the safety and efficacy of the use of APC on endoscopic treatment of peptic ulcer bleeding. Methods:In this trial, a total of 18 patients(M:F=11:7) with bleeding peptic ulcers(gastric ulcers: 12 patients, duodenal ulcers: 6 patients) received APC. According to Forrest classification, Ia was revealed in 8 patients, Ib in 6, II in 4. For APC we used the Soring/Quick born unit. We assessed the hemostatic rates, rebleeding rates, and complication rates retrospectively. Results: After APC, hemostatic rates were 63%(5/8) in Ia, 100%(6/6) in Ib, and 100%(4/4). The rate of rebleeding after initial hemostasis was 13.5% (2 of 15 patients). 3 patients were failed initial hemostasis after APC. 2 of 3 patients received injection sclerotherapy and 1 of 3 hemoclipping and all 3 patients were permanent hemostasis. No major complication was observed in APC. Conclusions: APC seems to be effective and relatively safe for the treatment of peptic ulcer bleeding. There was lower initial hemostasis rate in Ia (spurting type) than Ib or II. A longer follow-up period however,and comparative trials with other treatment modalities are necessary.