Clinical aspects of convulsive and non-convulsive status epilepticus observed in 14 among 27 patients with Lennox-Gastaut syndrome were studied. Denominations were given to the manifestations not previously mentioned in the literature, according to the quality and eventual sequence of observable phenomena, in agreement with the terminology used by the Clinical and Electroencephalographical Classification of Epileptic Seizures. The incidence and prognostic significance of status were discussed. A classification of the status epilepticus was suggested according to its incidence, always high, and according to the frequency of atypical forms.