Case report of a progressive cerebellar syndrome with generalized myoclonic movements, which generally appear with the closing and sometimes with the opening of the eyes, but constantly with luminous stimulation. The myoclonic movements were not observed on the palate and were not affected by barbiturates. The cerebellar syndrome was global, with the neocerebellar symptoms predominating over the paleocerebellar ones; the disease had a progressive evolution with periods of partial remission. Of particular interest were the EEG results which showed several spike-wave and multispike-wave complexes of large amplitude, bilateral and synchronic. In the intervals between the attacks the electric activity seemed to be constituted mainly by waves between 6 and 9 c/s, with a higher voltage on the posterior areas. Paroxysms appeared with open as well as with closed eyes; they appeared always when the patient closed her eyes, being generally accompanied by generalized myoclonic attacks. Isolated luminous stimulations, even of a relatively small intensity, did always lead to electric paroxysms with generalized myoclonic attacks, mainly of the lower limb. Intermittent luminous stimulation at frequencies of 1, 2, 3, 5, 10 and 15 per second, produced rhythmic spicules of the same frequency as the stimulation, followed by slow waves at low frequencies.