Objective This study was undertaken to assess the safety of trial of labor after previous cesarean delivery. Study design Retrospective cohort study of 308,755 Canadian women with previous cesarean delivery between 1988 and 2000. Occurrences of in hospital maternal death, uterine rupture, and other severe maternal morbidity were compared between women with a trial of labor and those with an elective cesarean section. Results Rates of uterine rupture (0.65% ), transfusion (0.19% ), and hysterectomy (0.10% ) were significantly higher in the trial of labor group. Maternal in hospital death rate, however, was lower in the trial of labor group (1.6 per 100,000) than in the elective cesarean section group (5.6 per 100,000). The association between trial of labor and uterine rupture was stronger in low volume (< 500) than in high volume (≥ 500 births per year) obstetric units. Conclusion Trial of labor is associated with increased risk of uterine rupture, but elective cesarean section may increase the risk of maternal death. Objective This study was undertaken to assess the safety of trial of labor after previous cesarean delivery. Study design Retrospective cohort study of 308,755 Canadian women with previous cesarean delivery between 1988 and 2000. Occurrences of in hospital maternal death, uterine rupture, and other severe maternal morbidity were compared between women with a trial of labor and those with an elective cesarean section. Results Rates of uterine rupture (0.65%), transfusion (0.19%), and hysterectomy (0.10%) were significantly higher in the trial of labor group. Maternal in hospital death rate, however, was lower in the trial of labor group (1.6 per 100,000) than in the elective cesarean section group (5.6 per 100,000). The association between trial of labor and uterine rupture was stronger in low volume (< 500) than in high volume (≥ 500 births per year) obstetric units. Conclusion Trial of labor is associated with increased risk of uterine rupture, but elective cesarean section may increase the risk of maternal death.