Delay in healing of the perineal wound is a major cause of disability in patients after excision of the rectum. The outcome of primary suture in 76 patients treated at St Mark's Hospital between 1967 and 1976 was correlated with a number of factors describing the patients, their preparation for surgery and details of surgical technique and management. The perineal wound healed by first intention in 33 patients. The remaining 43 patients regarded as failures included 7 with delayed breakdown after initial healing. The results showed that women fared better than men. Excision of the rectum following colectomy and ileostomy was associated with failure of the perineal wound to heal in 9 out of 10 patients. Treatments with peroperative ampicillin and topical antibacterial agents were both correlated significantly with success. Preoperative sepsis and operative contamination were followed by perineal sepsis and wound breakdown on 16 out of 21 occasions. Discriminant analysis showed that topical and peroperative antibacterial treatments, sex, preoperative sepsis and finally ACTH were the most important variables in descending order of importance. The prediction of success and failure by this procedure was 72.4 per cent correct.