To assess the postoperative analgesic effect of intrathecal morphine, it was given with 0.5% isobaric bupivacaine intrathecally after orthopedic surgery. The patients were divided into three groups. In group l(control group) 0.5% bupivacaine 3ml was administered with normal saline 0.2ml to 10 patients. In group ll (experimental group) 0.5% bupivacaine 3ml was administered with morphine hydrochloride 0.5mg to 10 patients and in group lll (experimental group) morphine hydrochloride 1.0mg to 10 patients. The duration of the postoperative analgesic effect, fequency of analgetic jection and incidence of side effects were checked and compared. The results of this study were as follows: 1) The mean time of duration of analgesia was prolonged significantly in group ll compared to group l (p<0.05) and very significantly in gorup lll(p<0.005) and also significant sifference getween group ll and group lll(p<0.01). 2) The frequency of analgetic injection in the postoperative period was lower in group ll than in group l and no patien was injected in group lll. 3) The mean time to maximal analgesic block was 19.5 minutes and the mean time to maximal motor block was 17.7 minutes. There was no difference among the three groups. 4) The mean time of recovery from the sensory blockade and motor blockade was 6.1 hours and 4.2 hours. There was no difference among the three groups. 5) Among the three groups there was little change in a the cardiovascular system due to suppression of the autonomic nervous system after induction of spinal anesthesia. 6) In all groups the systemic complications occurred such as nauses, vomiting, micturition difficulty, itching, constipation, headache and backache. This complications did not appear to be dose dependent and not occurred in patients not receiving morphine. Severe delayed respiratory depression was noted 2 cases in group lll.