A retrospective review of a consecutive series of 685 adult patients undergoing tonsillectomy was conducted. Determinations were made of the post-tonsillectomy bleeding rate, the need for intervention to control bleeding, and the blood transfusion rate. Statistical analysis was used to determine whether bleeding rates differed according to three criteria: gender, indication for tonsillectomy, and age. Post-tonsillectomy bleeding occurred in 35 patients (5.1%); five of these patients experienced bleeding during the first 24 hours postoperatively, and the remaining 30 experienced delayed bleeding. When it occurred, the mean time lapse between tonsillectomy and bleeding was 6.9 days (+/- 4.1). Twenty of the 35 patients (57.1%) required a procedure to control their bleeding, but no patient required a transfusion. There was no statistically significant difference in bleeding rates based on gender, the indication for surgery (chronic tonsillitis, obstructive sleep apnea syndrome, or to rule out neoplasia), and age. These results indicate that (1) post-tonsillectomy bleeding occurs in approximately 1 of 20 adults independent of individual patient characteristics, (2) more than half of patients who bleed are likely to require a procedure to control their hemorrhage, and (3) the need for transfusion is distinctly unlikely.