In a prospective randomized study in children, we compared caudal bupivacaine-clonidine with bupivacaine-morphine to evaluate whether clonidine can be used as an alternative to morphine in caudal anaesthesia. Caudal anaesthesia was administered in 36 children undergoing orchidopexy, hernia repair or circumcision, using 1.5 mL kg−1bupivacaine 0.18% with either 1 μg kg−1clonidine (group 1) or 30 μg kg−1morphine (group 2). Haemodynamic and respiratory parameters, anaesthetic requirements, recovery time and pain score were monitored for 24 h. Eleven children in group 1 and nine children in group 2 did not need any supplementary systemic analgesics throughout the 24-h observation period. Mean (±SD) duration of analgesia in the remaining patients was 6.3 h (±3.3 h) in group 1 and 7.1 h (±3.4 h) in group 2 (P=0.43). Recovery time after anaesthesia was significantly longer in group 1 (16.6 ± 8.8 min) than in group 2 (11.5 ± 4.7 min) (P< 0.05). We conclude that analgesia provided by 1 μg kg−1clonidine added to caudal bupivacaine is comparable with that provided by 30 μg kg−1caudal morphine with bupivacaine. Clonidine at this low dose did not cause respiratory depression.