Fifty experimentally induced, standardized gastric bleeding lesions were successfully arrested in the dog using electrocoagulation with simultaneous instillation of water (EHT-coagulation). The contact pressure of the coagulating electrode was kept almost constant by means of a spring mechanism. The coagulated lesions healed without secondary enlargement of the coagulation effect and without complication. No secondary perforations were observed. Even when coagulation was carried out at an output power about 30% higher than the mimimum power necessary for reliable hemostatic coagulation, no complications were observed. Only with additional post bleeding arrest coagulation in excess of 10 seconds at this higher output, were two primary performations produced in 2 out of 12 cases. The non-perforated remaining 10 lesions healed without complication. With additional coagulation (at power output setting 6 for 20 seconds - 8 cases; at power setting 7 for 10 seconds - 6 cases), no perforations were observed and healing was without complications. Thus, in animal experiments, the therapeutic range for the arrest of bleeding using the electro-hydro-thermo-electrode is adequately large. The technique should be tested in clinical trials.