ABSTRACT.Patients with prolongation of the Q-T interval of the electrocardiogram are at risk for ventricular tachyarrhythmias which can lead to severe neurologic morbidity and mortality secondary to cerebral ischemia. Since these patients may present with seizures or syncope, they frequently receive their first diagnostic evaluation through the EEG laboratory. Electrocardiographic monitoring during an EEG examination is a simple and common practice but analysis for possible prolongation of the Q-T interval is not routinely performed. This paper discusses the importance and methodology of measuring the electrocardiogram Q-T interval on records obtained in the EEG laboratory.