Objective To evaluate the safety and analgesic efficacy of patient controlled intravenous analgesia (PCIA) with tramadol, and to compare its benefits and risks with combined spinal-epidural analgesia (CSEA)+ patient controlled epidural analgesia (PCEA). Methods Eighty American Society of Anesthesiologist (ASA) Ⅰ-Ⅱ at term parturients in active labor were randomly divided into 3 groups: the control group (n=30) received no analgesia; group A (n=30) received spinal administration with ropivacaine 2.5 mg and fentanyl 5 μg, then with PCEA; group B (n=20) received 1 mg/kg tramadol loading dose I.v.. PCIA with 0.75% tramadol and it included: PCA dose 2 ml, lockout time 10 minutes, background infusion 2 ml/h, total dose no more than 400 mg. The intensity of pain was evaluated using Visual Analogue Scale (VAS). Results Both group A and B showed good pain relief. VAS pain scores were significantly decreased in group A and B compared with those in the control group (P<0.01). In comparison with group B, the VAS pain scores decreased in group A (P<0.05). The onset times of analgesia in group A were shorter than those in group B (P<0.05). Apgar scores in group B were lower than those in group A (P<0.05). The periods of second stage of labor in group A were longer than those in the control group and group B (P<0.05). The cesarean delivery rate was significantly higher in the control group (16.7%) than in group A (3.3%) and group B (5.0%), but it did not differ between group A and B. There were no significant differences in vital signs, fetal heart rate, degree of motor block, and uterine contractions among the 3 groups. Conclusions PCIA with tramadol is now a useful altative when patients are not candidates for CSEA for labor, or do not want to have a neuraxial block anesthesia. However, sometimes it may not provide satisfactory analgesic effect.