Hypotension during caesarean section under spinal anaesthesia is a common complication. Several measures are used to reduce the incidence of hypotension but no method is fully effective. Prophylactic intramuscular ephedrine may be effective in reducing the incidence of hypotension in addition to conventional measures. To evaluate the efficacy of prophylactic intramuscular (IM) ephedrine (0.5 mg/kg, maximum up to 45 mg), given 10 minutes and 20 minutes before spinal anaesthesia to prevent hypotension, and to observe the adverse effects of IM ephedrine. A prospective, randomised, double-blind controlled study was undertaken where 150 pregnant mothers aged between 18 and 29 years and belonging to ASA physical status I, posted for elective caesarean section, were randomly allocated into one of the three groups. Group C received only preloading with 15 ml/kg of Ringer lactate (RL) solution, group E10 and group E20 received injection ephedrine 0.5 mg/kg IM 10 minutes and 20 minutes prior to performing spinal anaesthesia respectively along with 15 ml/kg RL preloading. The incidence of hypotension was significantly more in group C compared to other two groups. Mean arterial pressure and heart rate were significantly more in group E10 compared to group C. No significant increase in the incidence of hypertension and tachycardia in any group were observed. The findings of this study indicate that prophylactic IM ephedrine 0.5 mg/kg given 10 minutes before spinal anaesthesia gives better haemodynamic stability during intra-operative period without any significant increase in the incidence of adverse effects.