To evaluate the effect of a 20- or 60-second instillation period using 0.5% bupivacaine with epinephrine for pain relief after pediatric inguinal herniorrhaphy and hydrocelectomy. In a randomized, double-blind study, 103 children (aged 1 to 12 years, American Society of Anesthesiologists [ASA] physical status I or II) were allocated into 4 groups after induction of anesthesia. Group 1: normal saline 0.25 mL/kg instilled, which remained in the wound for 20 or 60 seconds before wound closure. Group 2: 0.25 mL/kg 0.5% bupivacaine with epinephrine 5 microg/mL instilled, which remained in the wound for 20 seconds. Group 3: the same quantity and dose of drug 2 instilled as group, but remained in the wound for 60 seconds. Group 4: an ilioinguinal and iliohypogastric block performed before operation using 0.5 mL/kg 0.25% bupivacaine with epinephrine. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and Aldrete-Kroulik recovery scores were used to monitor postoperative pain and recovery status. Analgesic was given when the CHEOPS score was >/= 7 despite other supportive therapy. The number of patients requiring analgesics within 2 hours in group 1 (73.1%) was more than groups 2, 3, and 4 (23.1%, 20.8%, and 16%, respectively, P <.001). The median time to first analgesic in group 1 (50 minutes) was also less than groups 2, 3, and 4 (420, 525, and 425 minutes, respectively, P <.0001). 0.5% Bupivacaine with epinephrine for as short an instillation period as 20 or 60 seconds can provide a good analgesic alternative after herniorrhaphy and hydrocelectomy in pediatric patients. All studied blocks had comparable duration of action.