Background and Objective: Childbirth is an important event during a woman’s life and the second stage of labor is extremely painful. There are disagreements regarding the most appropriate position during this phase. The main aim of this study was to compare the effects of different positions during the second stage on the length of labor. Materials and Methods: A randomized clinical trial was designed for women who were referred to the Taleghani Hospital in Arak between the years 2009-2010 for delivery. The inclusion criteria were set as women being primiparous and singleton, within the gestational age of 37-42 weeks. Demographic data and BMI forms were completed for the participants, and after signing the consent forms, they were randomly allocated to three groups: group1, lithotomy position (n=49) group2, squatting position (n=49) and group3, kneeling position (n=50). All participants were laid in their respective positions after full dilatation and effacement until the crowning stage of the fetus. The times between full dilatation and effacement until the crowning stage were measured by chronometer and Apgar score. Results: A total of 148 women with the mean age of 24.35 ± 3.36 years participated in the study. We found no significant differences in the mean duration of the second stage of labor among the 3 groups: 49.02 ± 26.31, 50.97 ± 25.68, and 52.71 ± 26.52 minutes for lithotomy, squatting, and kneeling positions, respectively). The rates of the cesarean sections in lithotomy, squatting, and kneeling position groups were 5.76%, 7.54%, and 9.1% respectively. These differences were not statistically significant. There were also no significant differences in 1- and 5-minute Apgar scores between the 3 groups. Conclusion: Although in contrast to some other studies, we did not find a significant correlation between different labor positions and the duration of the second stage of labor, it seems advisable to select the most comfortable position per case basis so that women feel the least pain and are provided with the maximum comfort and calm possible.