ABSTRACT.Severe, acute disorders of the central nervous system account for a large proportion of patients seen in neurointensive care units (NICUs). In such cases of actual or threatened brain damage, it is necessary, for diagnostic, therapeutic, and prognostic purposes, to be able to ascertain and to monitor underlying cerebral function. An increasingly sophisticated battery of tests is available to help establish a correct diagnosis in the critically ill patient, including neuroradiologic techniques such as CT and MRI imaging and neurophysiologic studies such as EEG and evoked potentials (EPs). Research tools, such as magnetoencephalography and PET scanning may come into more widespread clinical use in the future. In addition to their usefulness in evaluation of anatomic and physiologic function at a particular moment, some of these techniques may prove adaptable to providing continuous monitoring of cerebral metabolic activity. At the present time, however, the single best monitoring tool is the serial examination at the patient's bedside, and this remains the mainstay of neurointensive care medicine. In certain situations, such as profound coma or therapeutic barbiturate anesthesia, the exam provides less helpful information. Circumstances also arise in which changes in the neurologic examination occur late in the course of serious deterioration. Therefore, for a number of reasons, there exists a need to find ways to monitor brain function that will yield consistent data having premonitory power. Neurophysiology has much to offer to the NICU in meeting these needs for diagnostic assistance, trend monitoring and prognostication. The use of standard and computer assisted EEC has been recently reviewed (Hack 1985, Hansen et al. 1986, Prior 1985) and this paper will briefly discuss the use of EPs in the NICU setting.