The French study on sexual aggressors that took place between 1993 and 1996 in eighteen regional medico-psychological wards compares two kinds of pupulations. One of sexual aggressors and another of aggressors in terms of voluntary blows (witnesses). Such a study shows that the sexual aggressors had been in the past children and adolescents far better integrated than the witnesses within the school circuits. Yet, very early, analyses of their nightmares show with this population a feeling of severe insecurity leading to far more psychological or psychiatric consultations for sleep disorders both in childhood and in adolescence. Among the motives for consultations (which are twice as many as those demanded from the group of witnesses) one can already find out specific sexual behaviours and typical sexual aggressions. Severe sadistic relationships and a premature tendency to serious crualty towards animals (even pets) are one of the major characteristics of sexual agressors. The other major characteristic is that, in one case out of three, a sexual aggression before the age of ten which will be in 75% of the cases repeated in the course of childhood or of adolescence. Yet the analysis of the beginnings of the sexual life of such subjects shows that a greater number of them have been the victims of sexual abuse by either men or women from their surrounding without their being able to analyze such acts as being aggressive. This leads the author to suggest the hypothesis according to which there would exist for such subjects of a ” continuous primary seduction ” in which the aggression act, usually presented as an ´initiationª would thus become a ´logicalª achievement. Finally, such a study shows that acting sexual aggression works as an anti-depressant from adolescence onwards.