Objective. To assess the effects of audit and feedback on the practice of professionals in obstetrics. Design. Before-after intervention study. Setting. Obstetric unit of a university hospital in Brazil. Methods. Before the intervention the prevalence rates of six evidence-based interventions were assessed. Seminars and workshops were administered, with the baseline results and also the main contents from systematic reviews on the topics studied, followed by detailed discussion of each topic, based on the Reproductive Health Library. After four months, the same practices were measured again and compared with the pre-intervention period. Main outcome measures. Selective episiotomy; continuous electronic fetal monitoring (EFM) during labor of low-risk pregnant women; antibiotic prophylaxis in cesarean section; active management of third stage of labor; routine induction of labor at 41 weeks for uncomplicated pregnancies; and continuous support for women during childbirth. Results. Both periods showed a similar number and mode of deliveries. There was a significant reduction in episiotomies (RR = 0.84; 0.73-0.97) and an increase in continuous support for women during childbirth by a companion (RR = 1.42; 1.24-1.63). Although there was not a significant change in the use of oxytocin during the third stage of labor, there was a shift to the internationally recommended dosage of 10 IU (p<0.0001). There was no significant change in the use of antibiotic prophylaxis for cesarean section, continuous EFM, or routine induction of labor at 41 weeks for uncomplicated pregnancies. Conclusion. Audit and feedback can be used as a tool to improve obstetrical practice, at least for some interventions and when the medical staff is open and receptive to change.