The five subjects were detected among the 700 inmates of a large Austrian prison by means of the Quinacrinfluorescence method and subsequent lymphocyte cultures. Family and criminal histories were compiled for each subject, and supplementary information was gathered through psychological observations, physical examinations, and intelligence and personality tests. As a result, a number of characteristics were identified which had been previously linked to enhanced risks of criminal activity; however, a direct connection between these characteristics and the XYY caryotype syndrome was not discovered. All of the subjects came originally from farm-worker families in which problems such as alcoholism and broken marriages were recorded. The criminal offenses which had been committed varied from subject to subject so that no clear relationship could be drawn between offense types and the XYY caryotype characteristic. Each of the subjects had been convicted for between 5 and 25 offenses and had spent between 4 and one-half and 15 and one-half years in jails (ages: 23, 23, 31, 48, and 55 years). Theft and burglary were the most common offenses. Acute physical problems could not be found, although three subjects had smaller than normal testicles. The lack of meaningful relationships with other persons was noted in four subjects. Three subjects had below average intelligence, a fourth had normal scores, and the fifth refused to be tested. The personality tests revealed above-average psychopathic tendencies in all four subjects who agreed to participate. These four subjects also demonstrated a tendency towards irritability and feelings of frustration and a lower than average ability to control their drives. Related studies are reviewed. Data tables are not provided. A reference list (27 entries) is included. --in German.