Abstract Nine patients with the association of Hirschsprung's disease (HD) and anorectal malformation (ARM) were treated at the Children's Hospital, Bangkok, Thailand during the 10-year period between 1977 and 1986. Four cases had the low type of ARM, four had the intermediate type, and one had the high type. Aganglionosis involved the rectum only in four cases, extended up to the rectosigmoid in three, up to the sigmoid in one, and involved the whole colon and the last 15 cm of the ileum in the other. A transitional zone was noted in the loopogram films after the initial colostomy for ARM in two cases. Barium enema was performed in six cases. Evidence of ultrashort segment aganglionosis was noted in one case. A transitional zone was noted in one case, but was not present in the remaining four cases. Delay of diagnosis of the associated HD in some cases was due to the atypical symptomatology and radiological findings. The association of these two conditions may probably be more common than generally recognized.