An increased incidence of neoplasia at the site of ureterosigmoidostomy must be considered in patients being evaluated for or who have undergone this procedure. A case of mucinous adenocarcinoma 24 years following bilateral ureterosigmoidostomy is reported. This patient had bilateral hydroureteronephrosis, which led to left nephroureterectomy and right cutaneous ureterostomy. Mucinous adenocarcinoma was diagnosed only after the edematous, protruding and inflamed cutaneous ureterostomy stoma was biopsied. To our knowledge this is the first reported case of transfer of such a malignancy to the skin at the time of cutaneous ureterostomy. We recommend that ureterosigmoidostomy be performed only in patients with a limited life expectancy who agree to long-term followup. This followup should be frequent, complete and continue for the remainder of the patient's life. We consider the tendency for development of neoplasia at the ureterosigmoid anastomosis to be a relative contraindication to ureterosigmoidostomy. However, with proper patient selection and followup, ureterosigmoidostomy is still a remarkably satisfactory method of urinary diversion.