OBJECTIVE: To evaluate potential risk factors and the incidence of bleeding following adenoidectomy or tonsillectomy, with or without adenoidectomy requiring surgical treatment under general anesthesia. STUDY DESIGN AND SETTING: Retrospective chart review of 15,218 patients who underwent surgery between January 1, 1988, and September 30, 2001, at our institution (St. Anna Hospital, Duisburg). RESULTS: A total of 229 patients experienced postoperative bleeding (1.5%). Patients of male gender and 70 years of age or older were significantly at risk for post-tonsillectomy hemorrhage. The incidence of bleeding increased with age. Of the bleeding episodes, 76% occurred on the day of surgery; immediate abscess-tonsillectomy was not associated with an increased risk of bleeding. CONCLUSIONS: Hemorrhage following tonsillectomy and adenoidectomy is rare and predominantly occurs early after surgery. Male patients, 70 years of age or older, infectious mononucleosis, and a history of recurrent tonsillitis were identified as risk factors for post-tonsillectomy hemorrhage. Delayed hemorrhage has the potential to be life-threatening.