The efficacy of magnesium sulfate was evaluated as the primary tocolytic agent in the management of patients at risk for premature delivery. Fifteen patients presenting with premature labor between 28 and 35 weeks gestation, given titrated dose intravenously magnesium sulfate till uterine contraction ceased, were prospectively studied. All patients received an additional oral beta-mimetic agent once labor was arrested till 36 weeks gestation. All cases had intact membranes and no contraindications for tocolytic therapy. Tocolysis for more than 72 hours was achieved in 14 cases (93.3%). Delayed tocolysis of more than 7 days was achieved in 13 cases (86.7%). The mean dosage to achieve tocolytic effect was 3.17 g/hr (SD 0.08). The mean serum magnesium level to achieve such effect was 5.38 mg/dl (SD 0.88). Magnesium sulfate was found to be easy to administer and clinically efficacious with minimal adverse effects. It may be used as the first line of tocolytic therapy where beta-sympathomimetic drugs are contraindicated.