Objective:The efficacy of ultrasonographic cervical assessment before induction of labor in predicting the success of labor induction in primigravid women.Methods:This is a prospective study conducted in 50 women who underwent transvaginal ultrasonographic cervical length and posterior cervical angle measurements alone or together before induction of labor.Results:Induction of labor was successful in 38 (76%) of the women. Multiple logistic regression analysis demonstrated cervical length and posterior cervical angle assessed by transvaginal sonography as independent predictors of successful outcome after induction of labor. The cut-off point for the parameters in receiver operating characteristics curve was 2.5cm for cervical length and 90° for posterior cervical angle. Cervical length of 2.5 cm had a sensitivity of 84.2%, and a specificity of 91.7% and a posterior cervical angle of 90° with 65.8% and 75%, respectively.Conclusions:Transvaginal sonographic assessment of cervical length and posterior cervical angle is better than conventional Bishop score in predicting successful labor induction in nulliparous women.