OBJECTIVE We report the 5-year interval change in voiding function of orthotopic ileal neobladder. METHODS Voiding function was evaluated at two points with an interval of 5 years in 49 patients with orthotopic ileal neobladder. The first and second surveys were performed in May, 1998 (1998 survey) and in April 2003 (2003 survey), respectively. Median age at operation was 67 years, ranging 47-77. Median follow-up times at the first and the second surveys were 19.5 months (range, 3-87) and 67.5 months (range, 62-145), respectively. RESULTS There was no significant change in daytime continence status between the 1998 and 2003 surveys. More than 95% never or only occasionally suffered daytime incontinence in the two surveys. On the other hand, 15 (34.1%) and 14 (31.8%), respectively, experienced night-time incontinence, despite regular voiding during the night. When voiding patterns were analysed, 11 patients (23.4%) sometimes or often performed catheterization because of difficulty in urinating or incomplete emptying of the neobladder in the 1998 survey. Three patients (6.4%) were unable to void and required regular catheterization. In the 2003 survey, however, such poor voiders increased to nine (19.1%), although the difference was not significant. During the study period of 5 years, there was no change in renal function. CONCLUSIONS Continence status, either at daytime or at nighttime, was stable during the study period. The number of the patients who needed regular catheterization tended to increase, suggesting deterioration of voiding function with time. Careful long-term follow up is warranted.