Henri Gastaut was educated in neurology and neuroanatomy at the University of Marseille, graduating M.D. in 1945. In 1953 he became head of the neurobiological laboratories. He was appointed professor of anatomical pathology in 1954 and director of the regional centre for epileptic children in 1960. In 1973 a chair of clinical neurophysiology was established for him, a tenure he held until he was emerited in 1984.
His major interests were the study of electroencephalography and brain function in epilepsy. From 1957 to 1968 he was secretary general and from 1969 to 1973 president of the International League Against Epilepsy.