Pericentric inversion of the human Y chromosome has an estimated frequency of the one per thousand. This inversion is always inherited but also is possible a de novo presentation. Sometimes this inverted chromosome is associated with the Down, Klinefelter and other chromosomal syndromes. For the carriers of pericentric inversion the risk of the mental retardation or multiple abortion is not apparently increase and there is not relation with abnormal phenotypic features. The pericentric inversion of the human Y chromosome is only a rare chromosomal heteromorphism. Chromosome analysis of the father is advisable to determine whether or not the inversion is familial in order to be able to provide genetic counselling. Cytogenetic analyse, the karyotype of male fetus, other brother's and his father's were exhibited as 46,X, +mar (Y), inv(Y) (p11.2 →q11.2). His mother's was 46,XX. In these cases, it was concluded that there was no clinical significance because the fathers and male fetuses had the same pericentric inversion. The same abnormality was found in other members of the family. All of them have not abnormal phenotypic features. This finding suggests that the pericentric inversion of the Y chromosome affects neither the phenotype nor reproductive performance.