Abstract Electroencephalography (EEG) and continuous EEG (cEEG) are used to diagnose nonconvulsive status epilepticus and seizures, which are associated with an increased risk of morbidity and mortality; EEG and cEEG also can increase the yield of detection. The ability to detect seizures requires a high-quality cEEG recording, obtained by using a full montage of electrodes (ideally, imaging-compatible cup electrodes). Periodic patterns of indeterminate importance are in the ictal-interictal continuum and require consideration of the clinical state and the underlying cause. After cardiac arrest, cEEG provides important prognostic information about comatose patients. Other uses of cEEG include detecting delayed cerebral ischemia and monitoring the depth of suppression from barbiturate treatment.