The Autors show a case of research of maternity in the subject of alteration of social condition in comparison of two newborns, this is a case in which a maternity staded could be excluded, and a maternity denied could be recognized, on the base of the genotypes in connexion to the qualities of the specific-groups Rh.

The gynaecological exam of the two women and the determination of the types ABO and MN had not allowed the complete solution of the problem which was, on the contrary, reached and showed by the acknowledgement of the genetics formulas Rh.