The status epilepticus (SE) is a condition characterized by prolonged or repeated seizures over a period of at least 30 min. Neuropathologic consequences of SE are mostly due to continuous excitation of neurons. This recognition has led to an expansion of SE definition to include disorders in which clinical manifestations are subtle or atipical but have sustained and prolonged excitation of neurons recorded by surface or depth electrodes. In this article, we review the electroclinical features of SE. In secondarily generalized convulsive SE, there is a predictable progression of clinical and electroencephalographic (EEG) changes; clinical sings become increasingly subtle, whereas continuous or periodic epileptic discharges are seen on the EEG (electroclinical disassociation). Complex partial SE (CPSE) often goes unrecognized or is mistaken for behavioral or psychiatric disturbances; EEG could be difficult to distinguish from absence status, and needs rapid and vigorous treatment because permanent sequel can occur. SE is sometimes difficult to diagnose in encephalopathic epilepsy; an EEG criterion is the definitive change from the preictal state. EEG is the most useful test in SE; not only it serves to support the diagnosis of SE, but also to monitorize a successful treatment if the patient does not recover the neurologic function.