The renal function of sixty one adult patients was monitored by 99mTc-DMSA renal scan after cystectomy for a malignant tumour followed by ileal conduit urinary diversion. The postoperative follow-up period was 10 years. The stenosis rate of the uretero-ileal anastomosis was 12.8% and the incidence of pyelonephritis was 8% The mean value for overall renal function and for the function of each kidney did not deteriorate significantly (p = 0.1 and p = 0.7, respectively) over time. However, 26% of kidneys evaluated at 1 year and at 5 years showed a markedly decreased uptake on the renogram. In 70% of cases, this decreased uptake was related to the development of stenosis of the uretero-ileal anastomosis or pyelonephritis. Renal function remained stable at 5 years in group A, corresponding to patients with good initial renal function (n = 22, p = 0.07), and in group B, corresponding to patients with poor initial renal function (n = 7, p = 0.9). Similarly, the function of solitary kidneys did not deteriorate over the 5-year postoperative follow-up period (n = 7, p = 0.5). The functional value of the kidneys was therefore not globally altered after ileal conduit urinary diversion. The existence of a mechanical or infectious complication should be systematically investigated in the presence of a deterioration in renal function. DMSA isotope renal scan is a complete, qualitative and quantitative, follow-up examination after this type of urinary diversion. However, it is a second-line examination requested to assess the renal implications of a complication primarily detected by renal ultrasonography, which should be performed regularly after ileal conduit urinary diversion.