Electroconvulsive therapy (ECT) has been used in the treatment of psychiatric disorders such as schizophrenia and major depressive disorders which are resistant to pharmacologic therapy. Seizure duration is a major determinant of treatment efficacy in ECT. Patients requiring ECT need effective sedation and neuromuscular blockade to prevent discomfort and the possibility of fractures of bones during ECT. The Bispectral Index (BIS) reflects the clinical degrees of consciousness during sedation and hypnosis with intravenous and inhalational anesthesia. This study was performed to investigate if there is any correlation between the BIS and seizure duration in the patients with psychiatric disorders during ECT under propofol and succinylcholine anesthesia. A total of 11 patients with schizophrenia and major depressive disorders were monitored for BIS, electroencephalogram (EEG) and seizure duration. Seizure was detected using isolated forearm technique (IFT). The BIS was recorded at four specific time points (baseline before the start of anesthetic induction, before ECT (Pre-ECT BIS), at eye opening to verbal command and at 5 minutes after eye opening). Awake baseline value of the BIS showed significant changes depending on the depth of anesthesia at specific time points after propofol was administered. Pre-ECT BIS was positively correlated with seizure duration.