PURPOSE: Secondary bleeding is an inevitable and a troublesome complication of hemorrhoidectomy. This study analyzed the factors related to secondary bleeding after hemorrhoidectomy. METHODS: A total of 14,062 patients received a hemorrhoidectomy from Apr. 1999 to Apr. 2001. A retrospective study of 83 patients with secondary bleeding was done. At first, the doctors were divided into two groups. In one group, each doctor had performed more than 500 hemorrhoidectomies; in the other groups, each doctor had performed less than 500 hemorrhoidectomies. The incidence of secondary bleeding of the two groups was compared. Then, 155 patients without secondary bleeding were randomly selected as a control group. Clinical aspects and laboratory data were compared with those of the bleeding group. RESULTS: The total incidence of secondary bleeding was 0.6%. The incidence for the group with experienced doctors was 0.5%, that for the other group was 1.3%. When bleeding patients were compared with the control group, the proportion of patients who received a blood transfusion within 1 week before operation was 12.1% in the bleeding group and 2.6% in the control group. The postoperative WBC count was increased more in the bleeding group. The percentage treated with metronidazole was 12% compared with 25.3% in the control group. The incidences of bleeding according to operation sites were 19.6% in the right anterior, 12.2% in the left lateral, 10.9% in the right posterior, and 8.4% in the posterior portion. CONCLUSIONS: Secondary bleeding after a hemorrhoidectomy is more prevalent with less experienced doctors, recent history of blood transfusion, less use of metronidazole, and specific location of the hemorrhoid, such as the right anterior and the left lateral site of the hemorrhoid pile.