A comparative analysis of Q-band polymorphisms was conducted in phenotypically normal individuals and couples with repeated spontaneous abortions. In the group of pathology reduction of the following phenomena was found: frequencies of brilliant fluorescence in bands 4p11q11, 14p11, 14p13, 15p11, 21p13; the mean numbers of the brilliant fluorescent segments per cell per individual; frequencies of extremely large ("marker") Q-bands. All these findings coincided with our earlier published data on reduction of the C-heterochromatin amount in the same group of pathology.