The present study describes 2 cases of a balanced reciprocal translocation in the C-group of autosomes. Familial translocation 46,XX,t(6;7) was found both in a woman cytogenetically examined because of a developmental anomaly of the internal genitals (uterus bicornis subseptus) and in her healthy mother. Chromosomal complement 46,XYt(8;10) was proved in the healthy father of a child showing clinical features of Down's syndrome with a karyotype 47,XY,21+. Q- and G-banding techniques were used for precise identification of the chromosomes involved in translocations.