Detrusor function was evaluated by vesico-urethral holter (VUH), a computerized recording system (Urodec 500), in 17 children with lower urinary tract dysfunction. Eight had neurogenic bladders, eight had minor voiding dysfunction, and one was incontinent after posterior urethral valve ablation. VUH was technically satisfactory in, and acceptable to, all patients. It was more accurate in evaluating the type of urinary tract dysfunction than conventional urodynamics in 25% of the male patients and in 32.5% of the female patients.