In this prospective study of 80 patients with active bleeding from the gastrointestinal tract a Doppler ultrasonographic investigation of the gastroduodenal ulcers was performed, in addition to immediate endoscopic examination. Admitted to this study were ulcers with the stigmata of acute bleeding, such as a visible blood vessel in the ulcer floor, a blood clot, or a black base and Forrest III lesions. In 52 patients Doppler ultrasonography was able to document unequivocally a superficial blood vessel. Complete agreement of endoscopic and Doppler results was obtained in only 49% of the cases. When a blood vessel was positively identified, local injection of epinephrine and polidocanol was carried out. Thereupon, in the further course, the acoustic signal was shifted into deeper regions or disappeared entirely. In 8% of the cases initial sclerosing was followed by a rebleed, which was again treated by injection therapy. None of the patients died of their GI hemorrhage. Endoscopic Doppler ultrasonography is a new and effective procedure that enables objectification of the endoscopic findings. It identifies the indication for proceeding to operative endoscopy and can monitor the effectiveness of the latter.