Micturition studies were performed pre-, inter- and postoperatively in a consecutive series comprising 148 unselected hypospadiacs, both short-term results (on average 1 3/12 years after the last operation) and long-term results (on average 6 3/12 years after the last operation) being recorded. The clinical material was subdivided into 6 age-groups and the results were compared with a control material comprising 176 males. Supernormal flow values were recorded preoperatively in 38% of hypospadiacs, normal values in 49% and subnormal in 13%. Interoperatively, after meatotomy had been performed in all hypospadiacs, normalization of the subnormal flow values was observed and supernormal values were recorded in 72% of the patients. Postoperatively, the supernormal flow values successively declined but the long-term results demonstrated supernormal values in 26% of the patients, while the remainder had normal maximum flow values. Preoperative micturition urethrocystography revealed pathological changes in 48/148: trabeculation in 29; trabeculation and diverticula in 5; and vesicoureteral reflux in 14. The highest incidence of changes was found in the age-group 4--10 years and the second highest in 2--4 years. Postoperative micturition urethrocystography revealed a successive regression of the pathological changes. The most marked regression was recorded when surgical treatment was started at the age of 2--4 years.