Electroconvulsive therapy (ECT) is commonly associated with acute hyperdynamic cardiovascular responses, and we hypothesize that intravenous lignocaine can blunt this response. We have measured the effect of lignocaine 1.5 mg/kg i.v. on heart rate and mean arterial pressure during electroconvulsive therapy. Furthermore, we also assessed seizure duration using both the cuff method and two-lead electroencephalography. We studied 25 patients using a randomized, double-blind, placebo-controlled crossover study design. Patients in the control group were given intravenous saline 0.075 ml/kg, and those in the lignocaine group were given intravenous lignocaine 2% 1.5 mg/kg, and this treatment was conducted one minute before intravenous propofol 1.5 mg/kg to induce unconsciousness. Succinylcholine 1.5 mg/kg was then administered intravenously and electrical stimulation was administered after fasciculation. Measurements were taken at the baseline, prior to succinycholine, prior to electroconvulsive therapy and at the peak response after electroconvulsive therapy. Intravenous lignocaine significantly reduced the increases in heart rate after electroconvulsive therapy, as compared with the placebo. The use of intravenous lignocaine was, however, associated with a remarkably shortened seizure duration. Due to the reduction in seizure duration, routine administration of intravenous lignocaine may not be advisable since it may interfere with the psychotherapeutic efficacy of electroconvulsive therapy. However, intravenous lignocaine medication for electroconvulsive therapy is potentially useful for reducing tachycardia in high-risk patients and reducing the severity of propofol injection pain in comparison with a placebo.