We have developed a new classification for intravaginal testicular torsion by comparing the testes in 36 cases of intravaginal torsion with those of 30 cases undergoing castration for prostatic cancer. The classification was made by our new criteria as follows: bell-clapper type (type III) in which torsion very easily occurs; intermediate type (type II), which can be further divided into two subtypes, type IIb in which torsion easily occurs and type IIa in which torsion hardly occurs, and normal type (type I) in which torsion never occurs. We believe that our new classification is simple and useful for definite clinical understanding.