To compare the efficacy and side effects of 0.2 mg intrathecal (IT) morphine with 0.125% epidural bupivacaine, 62 women in labor were studied. They were randomly divided into three groups: group 1 (n = 20) received IT morphine; group 2 (n = 22) received epidural bupivacaine; and group 3 (n = 20) received a combination of both using a combined spinal-epidural (CSE) technique. According to a visual analogue scale for assessing analgesia, neither IT 0.2 mg morphine nor 10 ml 0.125% epidural bupivacaine was effective in producing adequate pain relief in labor, whereas the combination produced excellent analgesia. The use of IT morphine significantly reduced the dosage requirement of epidural bupivacaine. The incidence of nausea, vomiting, and pruritus was significantly higher when IT morphine had been administered, whereas that of urinary retention did not differ. No serious respiratory depression occurred in any of the patients. When the course of labor was studied, the prior use of IT morphine significantly prolonged the duration of the first stage of labor and the total duration of labor. We conclude that the administration of 0.2 mg IT morphine in combination with epidural administration of 0.125% bupivacaine provides better analgesia than the administration of either drug alone.