Early determination of outcome after out-of-hospital cardiopulmonary resuscitation is a common problem with great ethical, economic, social and legal consequences. Although there has been a fulminant development of emergency medicine during the last three decades, severe cerebral damage sometimes cannot be avoided. For neurological outcome prediction after cardiac arrest clinical neurological signs, electrophysiological examinations, neuroimaging tests, and laboratory parameters in serum and cerebrospinal fluid are used today, nevertheless, there still remains a considerable degree of uncertainty. However, although prognostic criteria which enable the clinician to stop treatment cannot be given at the present time, useful applications of early prognostication after cardiac arrest range from counseling of families, triage decisions, and do-not-resuscitate decisions to future clinical investigations of brain resuscitative measures.