Genetic diversity of the red deer Cervus elaphus (6 individuals from enclosures and 33 individuals living in the wild) and the sika deer Cervus nippon (30 individuals from enclosures) species was studied by using tissue samples from the legally hunted animals in Lithuania. Genotyping was based on seven microsatellites loci (STR) of nuclear DNA. The STR loci were variable, with 1 - 17 alleles and higher than intermediate values of heterozygosity (sika deer: H_o=0.695, H_e=0.694; wild red deer: H_o=0.626, H_e=0.624; red deer from enclosures: H_o=0.639, H_e=0.667). Among 69 individuals phenotypically designated as red deer and sika deer by hunters, based on Bayesian method 31 individuals had Q-values of 0.95–1.0 ("pure red deer"), 3 individuals had Q-values of 0.75–0.95 (hybrid of the "red type"), 2 individuals had values of 0.25 ˂ Q ≤ 0.75 (intermediate hybrid), 6 individuals had Q-values of 0.05–0.25 (hybrid of the "sika type"), and 27 individuals had Q values of 0–0.05 ("pure sika").

   Keywords: Cervus nippon, the sika deer, Cervus elaphus, the red deer, genetic variability, hybridisation, microsatellites.