Intrathecal opioids can provide labor analgesia. We attempted to prolong the duration of intrathecal sufentanil analgesia by adding epinephrine or morphine. Forty-one healthy, term nulliparae with cervical dilation < 5 cm participated in this double-blind, randomized protocol. Using a combined spinal and epidural technique, we gave intrathecal injections of either sufentanil 10 μg, sufentanil 10 μg plus epinephrine 200 μg, or sufentanil 10 μg plus morphine 250 μg. At baseline and every 5 min for 30 min thereafter, we recorded arterial blood pressure and asked the patients to rate their pain, nausea, and pruritus on visual analog scales. The women continued to rate these variables every 30 min until they requested additional analgesia. They then received 10 mL of 0.25% bupivacaine via the epidural catheter, and rated the above variables every 30 min until they requested additional epidural drug injection. Both morphine and epinephrine prolonged the duration of sufentanil analgesia. Only morphine prolonged analgesia after the first dose of epidural bupivacaine. However, because women in the morphine group experienced significantly more side effects throughout the study period, we do not recommend intrathecal morphine for labor analgesia.