Eleven survivors of pelvic rhabdomyosarcoma underwent bladder function studies and upper urinary tract evaluation at a mean of 6.6 years after completion of therapy, which included a conservative, bladder-sparing surgical policy. Primary tumour sites were: bladder base/prostate, 6; bladder dome, 1; vagina, 2; and pelvic side wall, 2. Seven children (five bladder base/prostate, one vagina and one pelvic side wall tumours) had received irradiation to the pelvis with external beam alone, brachytherapy or both. All seven of these patients had markedly reduced functional bladder capacity (11-48% of mean expected value for age) and abnormal voiding patterns, though bladder compliance was not reduced and bladder emptying was almost complete in five cases. Four of these children also had upper tract dilatation and two required reconstructive bladder surgery because of severe bilateral hydronephrosis. By contrast, each of four children treated without radiotherapy had a normal functional bladder capacity and a normal voiding pattern. all survivors of pelvic rhabdomyosarcoma, especially those who have received radiotherapy, should be carefully monitored for dysfunction of both lower and upper urinary tracts. The frequency-volume voiding chart is a sensitive and easily accomplished method of assessing bladder function in these patients.