Clinical observation and S.E.E.G. recordings performed with a surgical purpose in a typical case of startle-epilepsy has led to a reassessment of the relationship of this form of epilepsy and "Startle reaction". It is confirmed that the critical discharges take origin in the primary motor cortex. The authors discuss, in the light of experimental data already published, the physiopathological hypotheses likely to lead to a better understanding of startle epilepsy. On the one hand it is suggested that the startle reaction may be responsible through a feed-back mechanism for triggering the epileptogenic focus. On the other hand it is assumed that afferent pathways, central organization and efferent systems involved in startle reaction and actual fits are different.