Modified electroconvulsive therapy (ECT) is a safe and most effective treatment modality for major depressive disorders with suicidal tendencies. For this, one must have an ideal intravenous anaesthetic agent for induction which provides rapid onset, short duration of action, attenuates adverse physiological effect of ECT, rapid recovery without adverse shortening of seizure duration and minimum rise in serum potassium. The studies in search of an ideal intravenous anaesthetic agent are limited. Aim is to compare the effect of iv thiopentone, propofol and midazolam on induction time and quality, haemodynamics, Seizure duration, recovery time and changes in serum potassium level. 90 patients of ASA I and II of either sex having major depressive illness were randomly allocated into three groups (n = 30) based on iv induction agent used. Group I, Group II and Group III patients were induced with iv thiopentone 5 mg/kg, propofol 2 mg/kg and midazolam 0.2 mg/kg, respectively. The induction time, quality of induction, haemodynamic changes, seizure duration, recovery time and change in serum potassium level were measured and analyzed by Z test. Induction was quicker in propofol group i.e., 41.03 ± 6.11 sec than in thiopentone (50.6 ± 6.32 sec) and midazolam group (77.30 ± 6.67 sec). Seizure duration was significantly shorter in midazolam group compared to propofol and thiopentone groups. Though significant rise in HR, SBP DBP was observed in all the three groups following ECT, but rise was significantly higher in thiopentone group compared to other two groups. Significantly, faster recovery was observed with propofol. Rise in serum potassium after ECT was not significant in any of the groups. Propofol is a safe and suitable intravenous anaesthetic agent for induction of anaesthesia for modified ECT.