Abstract: In criminal cases,such as homicide and rape,because of the violence of criminal attacking or(and)victim defending,the blood or even pieces of human tissue from one or both sides of them remains on clothes of opposite or crime scenes.This is very important sometimes unique evidence of determing crime.Testing these cases we sometimes find that victim and suspect have the same blood groups and other biological phenotypes. Therefore the sex determination is of great value for these cases.In other cases,which difficult to identify the sex of corpse by surface examination,this test above is also of great value.In this paper we described a simple and rapid technique of sex determination from different biological materials by DNA amplification.Three cases were identified using this method.