The aim of this study was to determine the rate of paracolostomy hernia in relation to transrectal or pararectal position of a colostomy. Fifty-four consecutive patients who had undergone an abdomino-perineal excision for rectal neoplasia were studied. The location of the colostomy was assessed by physical examination. Computerised Tomography (CT) scanning was used in the cases where its anatomical position remained in doubt. The colostomy was in a pararectal position in 29 (54%), while in 25 (46%) it was transrectal. CT was necessary to determine the location of the colostomies in 9 cases (16%), eight of which had a parastomal hernia. The colostomy was pararectal in 15 (52%) of the 26 patients who had a paracolostomy hernia, and in 14 (48%) of the 28 patients without a paracolostomy hernia. No statistically significant correlation was found between the presence of a parastomal hernia and the position of the stoma in the abdominal wall.