Following an open clinical trial indicating that supplementation of 0.5% bupivacaine with fentanyl epidurally produced better intraoperative analgesia than plain bupivacaine, the authors designed a randomized double-blind trial involving 60 women with a singleton gestation requiring elective cesarean section. Epidural anesthesia was produced with all routine precautions employing 20 ml of 0.5% bupivacaine to which had been added, from coded ampoules, 2 ml of a solution containing either saline or 100 μg of fentanyl. Note was made of onset and duration of sensory and motor blockade, intraoperative analgesia (failed to excellent), time of worst intraoperative pain, neonatal condition, and fentanyl levels in umbilical venous and arterial blood and maternal venous blood.