A 17-year-old female underwent extensive orthopedic surgery of a knee under successful lumbar epidural anesthesia with lidocaine. Because significant pain was anticipated for several days postoperatively, continuous epidural infusion of fentanyl was planned. Following initial administration of 100 μg of fentanyl in saline, a continuous epidural infusion at 100 μg/h was initiated via a volumetric infusion pump. The pump tubing had 3 injection ports, with one port inadvertently left exposed. Several hours later an infusion of cephazolin (1 g in 50 ml of 5% D/W) was accidentally piggybacked into this exposed port rather than the intended IV tubing, with no awareness of this incident until 2 hours after its completion. The tubing was flushed with saline and changed. Fentanyl infusion was continued for an additional 24 hours without any evidence of short-term or long-term sequelae.