Subarachnoid hemorrhage is a serious neurological disorder that is often complicated by the occurrence of electrocardiographic abnormalities unexplained by preexisting cardiac conditions. These morphological waveform changes and arrhythmias often are unrecognized or misinterpreted, potentially placing patients at risk for inappropriate management. Many previous investigations were retrospective and relied on data collected in an unsystematic manner. More recent studies that included use of serial electrocardiograms and Holter recordings have provided new insight into the high prevalence of electrocardiographic changes in subarachnoid hemorrhage. Research on the prevalence, duration, and clinical significance of these electrocardiographic abnormalities and on associated factors and etiological theories is reviewed.