Since 1942, various experiments have sought to link specific encephalographic deviations with aggressive or psychopathic behavior. Findings of the author since 1952 have established that EEG patterns are not correlated to the nature of the crime but rather to the degree of impulsiveness with which the crime was committed. Brain wave variations in offenders include an alpha pulse frequency of 8 per second, as opposed to 10 for normal individuals; absence of theta rhythms; and the presence of posterior slow waves. Posterior slow waves in particular have been linked to behavioral difficulties in both juveniles and adults. Four groups of EEG patterns have been identified: 1) weak alpha rhythms, slow theta rhythms, and absence of posterior slow rhythms and of a reaction to hyperpnea; 2) ample alpha and theta rhythms, and sensitivity to hyperpnea; 3) high alpha rhythm frequencies, posterior slow waves, and reactions to hyperpnea; and 4) irregular alpha rhythms and diffuse theta rhythms. Delinquents are most prevalent in the latter two groups. The prospect of rehabilitation for established criminals is worst for individuals with EEG patterns of the first, near normal type, while reeducation possibilities are most promising for individuals within the third groups. The meaning of EEG results can only be assessed after comparison with findings of psychometric tests and other electrograms. A seven-item bibliography is supplied. --in French.