Abstract: It is known that the Causes of male sexual crime are complicated. Many investigntare believe that sexual offenders differ from non-sexual offenders in some physiological and biolgical ways. But there is only little biological research on it. The purpose of this study is to consider sexual offender ' s biological characteristics including the shape of external genitals, bled types, the distribution of XYY chromosome, plasma sexual hormones (T,LH,FSH) and the hair trace elements in 223 male sexual offenders in a prison. The results suggested that it is beyond doubt that there are some biological basis on sexual crime.

Key words: sexual crime, biological bases, blood type, XYY chromosome, sexual hormone, trace element