Epidemiologic studies of status epilepticus (SE) depend on clear definitions of terms. Such a definition is available for convulsive generalized SE, but clear definitions of nonconvulsive SE (NCSE) are lacking. This as well as clinical difficulties to diagnose NCSE are one source of underascertainment. The minimal incidence of SE in the Caucasian population of industrialized countries is about 20/100,000/year. It depends on age, ethnic background and possibly gender. Case fatality rates lie between 1.9 and 40% depending on age, etiology and duration of the SE. Effective treatment can improve and focal SE itself may impair case fatality. Clearly increased rates of long term case fatality in patients with symptomatic SE suggest that these patients should be considered a population at high risk.