Occiput posterior and transverse positions make up about one-fifth of all positions when labor begins and 5% at the time of delivery. These malpositions are accepted risk factors for a longer second stage of labor, instrumental and cesarean deliveries, and severe perineal lacerations. Manual rotation of the fetal head is sometimes used in an effort to reduce the need for cesarean delivery, but data on its success rate and safety are limited. This retrospective case-control study attempted to identify obstetrical conditions prevailing at the time rotation is attempted that help to predict its success or failure. Manual rotation was carried out in 796 patients during the study, and failed in 77 instances, 9.7% of the total. Rotation was performed only when dilatation reached 7 cm. One hundred forty-seven files (18% of all rotations) were analyzed, of which 68 were failed rotations and 79 were successful. On multivariable analysis, attempting rotation before full dilation approximately tripled the risk of failure (adjusted odds ratio [OR], 3.4; 95% confidence interval [CI], 1.3-8.6). Rotation done after failure to progress in labor increased the risk of failure compared with prophylactic rotation (adjusted OR, 3.3; 95% CI, 1.2-8.5). The cesarean delivery rate was markedly higher when manual rotation failed than when it succeeded (58.8% vs. 3.8%; P < 0.001). Success rates were similar for the occiput transverse and occiput posterior positions. All women who delivered vaginally after successful manual rotation delivered in the occiput anterior position, while those who delivered vaginally after failed manual rotation delivered in the occiput posterior position. Cervical lacerations occurred in only 2 patients, in whom manual rotation succeeded, but not in any of the failed cases. No woman in this study had a fourth-degree perineal laceration, but there were 2 third-degree lacerations in the failure group and 1 in the success group. The episiotomy rate was 44%. The incidence of severe fetal heart rate abnormalities during attempted manual rotation was 9.9%, and there were mild to moderate abnormalities in 19%; they did not appear to be associated with cesarean delivery.