Physical characteristics frequently associated with the double Y-chromosome are tallness, frequent nonspecific alterations in electroencephalographic patterns, and problems in sperm production. The anomaly occurs in about 1.1 percent of the population. Certain psychological weaknesses such as excessive aggressiveness, impatience, irritability, impulsiveness, an immature ego, and frequent passivity are connected with the condition. The frequency of the anomaly rises to 3.5 percent among mental patients and reaches 20 percent in prison mental wards. In this group, low intelligence levels and general psychological disequilibrium is much higher than in the double Y-chromosome population at large. Findings in literature are contradictory with regard to gravity of crimes and dangerousness attributable to delinquent double Y-chromosome carriers. But certain signs of early disturbances in the double-Y group have been verified: various malformations, precocity in physical development (at least with relation to size), psychological problems, and antisocial behavior. The association of the double Y-chromosome with certain somatic and psychological problems is certain but just how much the anomaly actually affects antisocial behavior is difficult to ascertain. The influence of environmental factors on the development of deviant behavioral patterns by double-Y carriers should not be underestimated. Many studies mention the high frequency of familial disturbances among double-Y carriers. Thus, the double Y-chromosome does not condemn an individual to a life of crime but may predispose him to react in a criminal fashion to certain stimuli. The aberration should be viewed as one factor conducive to crime among a number of others. Tables, notes and a 96-item bibliography are supplied. --in French.