Background Among the drugs used for induction of anesthesia for Electroconvulsive therapy (ECT), thiopental induces greater degree of cardiovascular alterations than other agents. Remifentanil has been found to reduce blood pressure and heart rate when administered as an adjuvant during general anesthesia, with unknown effects on duration of motor or EEG seizure activity during ECT. The purpose of this prospective, randomized, double-blind, placebo- controlled, crossover study was to evaluate the effects of supplementing thiopental anesthesia with remifentanil on convulsion duration and cardiovascular response during ECT.