The Lennox-Gastaut syndrome (LGS), although described earlier, was first accepted in 1966 as a form of severe childhood epileptic encephalopathy, characterized by refractory epileptic seizures of diverse types, typical EEG abnormalities and slow mental development. This condition, however, is surrounded by controversy as the clinical criteria used by various authors to define it are quite different. It is very likely that this eponym has been used to harbour distinct epileptic conditions, all of which have in common a slow spike and wave, complex in their EEG recording. Despite the fact that one of the hallmarks of LGS is an onset in early childhood, to add to the confusion, some cases of a LGS-like condition with onset in adulthood have been described. We report here one such case: a 28 year old man whose LGS-like condition started after severe head trauma at the age of 20. In addition we briefly íeview the difficulties in making this diagnosis, using this case to illustrate these aspects.