Objective: To compare anal sphincter function following spontaneous vaginal delivery and cesarean delivery, and assess the association of perineal length and sphincter injury with each delivery mode. Method: Perineal length was measured and anal manometric measurements were performed in 120 primigravidas before and after delivery. Results: Mean values for maximum anal resting and squeeze pressures were significantly lower after delivery irrespective of the mode of delivery, but there was a positive correlation between postpartum maximum anal resting pressure and perineal length (r=0.24, P<0.01). Conclusion: Anal sphincter function was disturbed after both vaginal and cesarean delivery, a finding weakened by the fact that almost half of the cesareans were performed for cephalopelvic disproportion identified during labor. (C) 2008 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.