The purpose of this study was to compare the efficacy and safety of intravenou s nitroglycerin with that of subcutaneous terbutaline as a tocolytic agent for e xternal cephalic version at term. We performed a prospective randomized trial. P atients between 37 and 42 weeks of gestation were assigned randomly to receive e ither 200 μg of intravenous nitroglycerin therapy or 0.25 mg of subcutaneous te rbutaline therapy for tocolysis during external cephalic version. The rate of su ccessful external cephalic version and side effects were compared between groups . Of 59 randomly assigned patients, 30 patients received intravenous nitroglycer in, and 29 patients received subcutaneous terbutaline. The overall success rate of external cephalic version in the study was 39%. The rate of successful exter nal cephalic version was significantly higher in the terbutaline group (55%vs 2 3%; P =. 01). The incidence of palpitations was significantly higher in patient s who received terbutaline therapy (17.2%vs 0%; P =. 02), as was the mean mate rnal heart rate at multiple time periods. Compared with intravenous nitroglyceri n, subcutaneous terbutaline was associated with a significantly higher rate of s uccessful external cephalic version at term. The purpose of this study was to compare the efficacy and safety of intravenou s nitroglycerin with that of subcutaneous terbutaline as a tocolytic agent for e xternal cephalic version at term. We performed a prospective randomized trial. P atients between 37 and 42 weeks of gestation were assigned randomly to receive e ither 200 μg of intravenous nitroglycerin therapy or 0.25 mg of subcutaneous te rbutaline therapy for tocolysis during external cephalic version. The rate of su ccessful external cephalic version and side effects were compared between groups. Of 59 randomly assigned patients, 30 The overall success rate of external cephalic version in the study was 39%. The rate of successful exter nal cephalic version was significantly higher in the terbutaline group (55% vs 23% ; P =. 01). The incidence of palpitations was significantly higher in patient s who received terbutaline therapy (17.2% vs 0%; P = .02), as was the mean mate rnal heart rate at multiple time periods. Compared with an intravenous nitroglyceri n, subcutaneous terbutaline was associated with a significantly higher rate of s uccessful external cephalic version at term.