In this article are studied 4 criminal patients, who acted under the state of epileptical twilight. The same as the literature concerning this subject, the observations are quite few, and that is justified by the rare possibility of tracing a typical twilight state, through the criminal history. From 873 inmates of the Manicomio Judiciário of the State of São Paulo (Brazil), between the period: Jan. 1, 1931-May 12, 1943, only 68 presented convulsive desorders of epileptical type, and 42 had commited crimes, directly dependent on the disease. Among the latter, only 15 became criminal in state of alteration of their usual conscience, and only in 4 cases, the deliquency was developped in twilight, state. The classification of this state was stablished according to the conception of Ruiz Maya, n'amely, a not very deep condition of unconsciousness, which appears frequently at the end of the convulsive attacks, lasting for long or short time, and of sudden termination. Another important characteristic, is the lacunar amnesia, which marks its onset and termination, being the delinquent act performed between these two periods. The observations are fully described: all the patients commited homicides or attempts. S. S. (case 1) shot his father when the latter tried to take him home. F. R. (case 2) strangled his wife, while she was taking care of his health. L. F. (case 3) killed a friend who helped him during a convulsive attack. In the case 4, the patient hurt to death a friend who, in company of his father, tried to reach him, in his uncontroled evasion after a motor attack. Concerning each patient, many tests were applied to find out the mechanism of these, apparently reasonless acts, specially the Rorschach test, the Jung-Bleuler test, the provoked hypnosis, and the reconstruction of the whole criminal and social history. The authors regret that a psychoanalytic study were not performed in these cases, but they felt this was out of their speciality, and they consider the principal finality of this work, to call the attention of the psychoanalysts for the subject. The 4 cases presented may well be divided in 2 groups. Cases 1 and 4 concern to individuals with a stronger criminogenous cause. Both of them suggest a strinking Edipe complex; they present clearly the rebellion against the paternal authority. Cases 2 and 3 are similar, in the fact that they have subconscious reasons. In both, as far as the authors could verify, never was there a conscious criminogenous intention. It seems to the authors, that jealousy, probaly besed in an inferiority complex, was what moved them to the crime. The A.A. conclude that every epyleptic who commits a crime, apparently with no reason, with alternation of the usual conscience, should be submitted to a psychoanalitic study. This would form a basis to a routine analysis of the personality of the epileptic among the criminals. Through this, the latent danger could be known, and perhaps, bases could be stablished for a criminal prophylaxis.