Castor oil was first noted to have oxytocic properties by ancient Egyptians. Derived from the castor plant Ricinus communis, castor oil may possess properties that are useful are in post-term pregnancies This study was performed at Khatam-Alanbia, hospital in shoushtar city in 1381.In this clinical trail 80 pregnant women, who had indication for induction of labor at term were randomly assigned to the study group (n=40), a single oral dose of castor oil, or assigned to a no treatment group (n=40).The castor oil was administered as a 60 ml dose diluted in orange juice.Inclusion criteria were singleton pregnancies with vertex presentation, intact membranes, and gestational age 40-42! week, Bishop Score of 4 or less, no evidence of regular uterine contractions and Gravity 1-2 Exclusion criteria were placenta previa, previous cesarean section or hystratomy, and maternal medical complications. All patients were observed for labor onset or 12 hours after castor oil administration. It labor was not occurred during this time, the patients were transferred to unit for oxytocine stimulation.The 2 groups of women did not differ in maternal age, parity, or gestational age. This study was performed at Khatam-Alanbia, hospital in shoushtar city in 1381. In this clinical trail 80 pregnant women, who had indication for induction of labor at term were randomly assigned to the study group (n=40), a single oral dose of castor oil, or assigned to a no treatment group (n=40). The castor oil was administered as a 60 ml dose diluted in orange juice. Inclusion criteria were singleton pregnancies with vertex presentation, intact membranes, and gestational age 40-42! week, Bishop Score of 4 or less, no evidence of regular uterine contractions and Gravity 1-2 Exclusion criteria were placenta previa, previous cesarean section or hystratomy, and maternal medical complications. All patients were observed for labor onset or 12 hours after castor oil administration. It labor was not occurred during this time, the patients were transferred to unit for oxytocine stimulation. The 2 group of women did not differ in maternal age, parity, or gestational age. Following the administration of castor oil, 25 of the 40 woman (62.5%) began active labor compared to 3 of the 40 woman (7.5%) receiving no treatment (p