BACKGROUND: The effect of epidural analgesia on the progress of labor is controversial. The objective of this study is to determine the effect of analgesia on the outcomes of labor, especially the cesarean delivery rate in the epidural and non-epidural (intramuscular nalbuphine) groups, prospectively. METHODS: All the nulliparous women were divided into two groups, group 1 (epidural group, n = 35) and group 2 (non-epidural group, intramuscular nalbuphine, n = 43) randomly. Epidural analgesia was maintained with a continuous epidural injection of 0.0625% bupivacaine with 0.2 microgram/ml fentanyl in group 1 and nalbuphine 10 mg was intramuscularly injected in group 2 when the cervix was dilated to at least 3-5 cm. The duration of the first and second stages of labor, cesarean delivery rate, Apgar score and body weight of infant were recorded and the pain score of parturient was recorded by 0-100 mm visual analogue scale. RESULTS: The duration of first and second stage were prolonged in the group 1 (epidural group). But there were no significant differences in the duration of first and second stage, Apgar score and body weight of infant between the two groups. Cesarean delivery rate was 16% (n = 7/35) in group 1 and 17% (n = 6/43) in group 2, so there was no significant difference between the two groups. Pain score was significantly lower in group 1 than in group 2. CONCLUSIONS: Epidural analgesia was not associated with increased cesarean delivery rate and provided safe and effective intrapartum pain control. Maternal-fetal factors and obstetric management, not epidural analgesia, are the most important determinants of the cesarean delivery rate.