The interrelation between of infestation by trematodes and genetic parameters in populations of three Siberian cyprinid species was studied. Positive correlation between the intensity of infection by trematodes and the level of individual multi-locus allozyme heterozygosity of fish was founded. Data on the differential infestation of different genotypes and the correlation coefficients between the frequencies of alleles and infection rate indicates conjugation of the spatial genetic structure of fish populations with resistance to trematode infestation.