We studied 24 boys who were randomized to receive caudal epidural anesthesia with 0.33 ml.kg.-1 0.25% bupivacaine either before (group A) or after (group B) Mathieu repair of distal hypospadias. The 2 groups did not differ in regard to age or weight, and all boys received a standardized anesthetic with halothane and nitrous oxide in oxygen. Intraoperative blood loss was measured with sponge weights and microcalibrated suction canisters. Halothane requirements were reduced in group A (0.5 versus 1.1 plus or minus 0.1%, p less than 0.001). Measured blood loss was reduced in group A (16 plus or minus 10 ml. versus 31 plus or minus 17 ml., p less than 0.01). Operating time was reduced in group A (92 plus or minus 13 minutes versus 103 plus or minus 14 minutes, p less than 0.05). There was no apparent difference in postoperative pain relief between the 2 groups. We conclude that caudal epidural anesthesia can reduce blood loss and improve surgical conditions during hypospadias repair.