Background: Endoscopic hemoclipping is known to be highly effective as hemostatic treatment for upper gastrointestinal bleeding. However, the efficacy and safety of hemoclipping for Mallory-Weiss syndrome (MWS) have not been reported. Thus, the aim of the present study was to assess prospectively the usefulness of endoscopic hemoclipping for MWS bleeding. Methods: This study was conducted from January 1994 to August 1999. Hemoclipping was performed when active bleeding (spurting, streaming or oozing), visible vessels or fresh adhesive clots were found on endoscopic examination. Patients who did not have any of these findings were conservatively treated. Follow-up endoscopy was performed within 24 hours, after 5 days and between 1 and 2 months after the procedure. Results: MWS was diagnosed in a total of 58 patients during the study. Hemoclipping was performed in 26 patients and was technically successful in all cases. The average number of hemoclips used was 2.8 ± 1.6 (range 1 to 8). The number of hemoclips required for hemostasis depended on the nature of the bleeding. No complications, recurrent bleeding, or deaths resulted. Follow-up endoscopy showed no evidence of hemoclip-induced tissue injury and no impairment of Mallory-Weiss tears. Conclusion: Endoscopic hemoclipping provided an effective and safe modality for obtaining hemostasis when bleeding is due to MWS. (Gastrointest Endosc 2001;53:427-30.)