BACKGROUND: Preterm delivery is a leading cause of perinatal morbidity and mortality and poses a challenge to obstetric practice as well as creating a major financial burden on the health care system. Consequently, extensive researches are being conducted aiming at predicting, preventing and optimizing the outcomes of patients with preterm contractions. There are various tocolytic agents being used with different mechanisms of action and efficacy for the prevention of preterm delivery. Thus comparing efficacy of some commonly used tocolytics such as magnesium sulphate and nifedipine will give ample opportunity to choose the tocolytic that gives better results in term of preventing preterm delivery. OBJECTIVE: To compare the efficacy of magnesium sulphate and nifedipine as tocolytic agents for the prevention of preterm contractions. DESIGN: A randomized clinical trial. METHODOLOGY In this trial, pregnant women with preterm contractions between 28 to 34 weeks of gestation presenting at the contractions ward of JUTH were randomly assigned to receive magnesium sulphate or nifedipine for tocolysis and the outcome in terms of preventing or delaying preterm delivery for >48 hours was compared. The common side effects of the two drugs were also noted. Randomization was conducted through sequential numbers in opaque envelopes generated from table of random numbers.