In the decade from 1981 to 1990, 30 patients underwent a posterior transsacral approach at the Aichi Medical University Hospital for their benign or malignant rectal lesions. The operation was classified into two procedures, consisting of the transsphincteric approach and transsacral approach, in order to cope with the condition of the anal sphincter muscles; whether they were divided or not. Eleven rectal tumors were successfully excised through the opened-up rectum by using the transsphincteric approach, and excellent results were obtained without any postoperative complications. Using the transsacral approach, 2 presacral dermoid cysts and 11 rectal lesions were easily removed under direct vision. Their prognoses were excellent. The transsacral approach was also applied for the resection of recurrent rectal cancers after a radical abdominoperineal resection in 6 patients suffering from intolerable local symptoms. All the patients were free from these uncomfortable local symptoms after the surgery. The posterior transsacral operation is thus considered to be of value not only for resecting benign rectal and presacral lesions, but also for resecting malignant rectal tumors in frail subjects who are unfit for radical operation and/or recurrent rectal cancer.