With the aim of evaluating, in a controlled prospective fashion, the efficacy of monopolar electrocoagulation in the emergency treatment of bleeding gastric and stomal ulcers, 37 patients were studied: 16 were electrocoagulated (EC group) while the remaining 21 were treated by conventional methods (control group). The hemorrhage recurred in only one of the 16 patients belonging to the EC group, but in 11 of the 21 control patients (p less than 0.0005). Transfusion requirements were also reduced in the EC group (p less than 0.05), with no significant difference in relation to mortality. Stratifying the results according to hemorrhagic activity, electrocoagulation should be clearly effective in those patients with spurting hemorrhage, taking into account several limitations: deep ulcers bearing gross vessels, and lack of cooperation by the patient. Prophylactic treatment of the bleeding ulcer with a visible non-spurting vessel may be indicated whenever we make a proper selection of the patients with a greater possibility of hemorrhagic recurrence.