Objective. To determine risk factors of failed labor in case of fetal macrosomia. Materials and methods. Medical charts of two hundred and forty six women who delivered macrosomic infants ( > 4,000g) between January 2004 and May 2005 were reviewed. Maternal and obstetrical data were analyzed by mode of delivery. Univariate and multivariate (logistic regression analysis) were performed to identify risk factors of failed labor. Results. Rate of cesarean delivery was 18.3% . Indications for cesarean were: failure to progress in 55.6% , arrest in fetal descent in 22.2% , fetal distress in 6.7% , and other in 8.9% . There was a higher risk of failed labor in nulliparous women (p < 0.001), in case of a symphysio-fundal measurements > 34cm (p = 0.004), in nulliparity associated with symphysio-fundal measurements > 34cm (p < 0.001), in case of previous cesarean delivery (p = 0.004), in cases of maternal height < 1.65m (p = 0.02), and with ocytocin use (p = 0.05). In multivariate analysis, nulliparity associated with symphysio-fundal measurements > 34cm (OR = 5.2; CI 1.5- 18.4), previous cesarean section (OR = 3.7; CI 1.1- 12.4) and maternal height < 1.65m (OR = 2.6; CI 1.2- 5.5) were independent factors of failed labor. Conclusion. Failure of labor in case of macrosomia can be predicted in the event of previous cesarean section, shorter maternal height, and association of nulliparity and symphysio- fundal measurements > 34cm. Objectives. To determine risk factors of failed labor in case of fetal macrosomia. Materials and methods. Medical charts of two hundred and forty six women who delivered macrosomic infants (> 4,000g) between January 2004 and May 2005 were reviewed. Maternal and obstetrical data Results of Rate of cesarean delivery was 18.3%. Indications for cesarean were: failure to progress in 55.6%, arrest in fetal descent in 22.2%, fetal distress in 6.7%, and other in 8.9%. There was a higher risk of failed labor in nulliparous women (p <0.001), in case of a symphysio-fundal measurements> 34 cm in nulliparity associated with symphysio-fundal measurements> 34 cm (p <0.001), in case of previous cesarean delivery (p = 0.004), in cases of maternal height <1.65 m In multivariate analysis, null (OR = 5.2; CI 1.5- 18.4), previous cesarean section (OR = 3.7; CI 1.1-12.4) and maternal height <1.65m independent factors of failed labor. Conclusion. Failure of labor in case of macrosomia can be predicted in the event of previous cesarean section, shorter maternal height, and association of nulliparity and symphysio-fundal measurements> 34 cm.