This was a prospective randomised, controlled, single-blind study done to determine the effect of intrathecal morphine 0.1 mg as compared with intrathecal fentanyl 25 microg in terms of analgesia and duration for postoperative pain relief after Caesarean section. Sixty ASA I or II parturients were randomised into two groups. Group 1 (n=33) received 1.8 ml of 0.5% hyperbaric bupivacaine combined with 0.1 mg morphine while Group 2 (n=27) received 1.8 ml of 0.5% hyperbaric bupivacaine combined with 25 microg fentanyl for spinal anaesthesia. Postoperatively, all patients were provided with patient controlled analgesia (PCA) morphine. Pain was assessed using visual analogue score (VAS) at 6, 12, 18 and 24 hours. Time to first demand of PCA morphine, cumulative PCA morphine requirement and opioid side effects were documented. The VAS for pain and the cumulative PCA morphine requirement were both significantly lower in Group 1 (p < 0.05) during the 24 hours study period. The time to first demand was also significantly longer in Group 1 (p < 0.05). Overall, there were no significant difference between the two groups in side effects, except for a high incidence of nausea and vomiting requiring treatment in Group B in the first six hours. In conclusion the addition of 0.1 mg morphine for spinal anaesthesia provided superior and longer postoperative analgesia after Caesarean section.