A questionnaire survey of ten institutions in Japan revealed that restorative proctocolectomy accounted for 81.8% of the surgical procedures performed in patients with UC in the last 5 years (1989-1993); ileoanal anastomosis (IAA) and ileo-anal canal anastomosis (IACA) were performed in 63% and 33% of these patients, respectively. Comparison of the two series showed that IACA was technically simpler and yielded better continence, but that it entailed a potential risk of recurrence of the disease in the remaining anal canal mucosa. Although IACA seems to be a useful surgical option for UC, until the long-term outcome of the procedure can be elucidated. It may be better regarded as a very low variation of IRA rather than as an improved technical version of IAA.