This study was conducted on 44 children aged 1-10 years, who had undergone lower extremity orthopaedic surgery under general anaesthesia. Patients were divided into two groups: Group 1 (n = 23) received buprenorphine caudally and Group 2 (n = 21) received buprenorphine intramuscularly, at the completion of the surgery. The dose of buprenorphine used in both the groups was 4 micrograms.kg-1 body weight. The quality and duration of postoperative analgesia were evaluated by a single observer using a 5-point score for the first 24 h postoperatively. The time until the patient required postoperative analgesic was recorded. The duration of analgesia was significantly greater with caudal buprenorphine (median 20.20 h) than with intramuscular buprenorphine (median 5.20 h). Of the patients in the caudal group, 43% did not require any supplemental analgesia during the first 24 h, whereas all the patients in the intramuscular group required supplements within 10 h postoperatively. Caudal buprenorphine (4 micrograms.kg-1 body weight) provided 10.8 h to more than 24 h of analgesia in children, with fewer side effects.