Urodynamic evaluation was performed on 8 of 62 boys (13 per cent) with persistent voiding difficulties after fulguration of posterior urethral valves. All had varying degrees of incontinence when evaluated. The striated muscle component of the external urethral sphincter was intact in each child. Five different types of bladder function were noted in the 8 children. Three boys had had a prior Y-V plasty of the bladder neck to improve upper and lower urinary tract emptying, which may have contributed to the subsequent incontinence. One additional boy had significant bladder neck obstruction requiring a unilateral bladder neck incision to improve voiding. Appropriate treatment plans were instituted based on the urodynamic findings of the bladder, bladder neck and external sphincter areas, and 6 of the 8 children are now completely continent.