A total of 596 hybrid pigs, crossbreeds (Czech Large White x Czech Landrace) x Pietrain from production testing were used in our study. Stress negative (NN) sows F1 and 9 different Pietrain boars with even proportion of RYR1 genotype (3x NN, 3x Nn, 3x nn) were included in the experiment. After slaughtering, the carcasses were divided into 4 weight groups with 10-kg intervals from 65 to 105 kg. The effect of genotype of RYR1 gene in boars on the thickness of back fat, meatiness and length of carcass has been demonstrated based on variance analysis. Back fat was deepest in all weight groups in the progeny of boars with heterozygote genotype. In contrast, the lowest values were obtained in the progeny of boars with recessive homozygote genotype (nn) (P < 0.001). The lowest values of meatiness were recorded in the progeny of boars with genotype Nn compared to the progeny of boars with genotype nn, the difference being statistically significant (P < 0.001). No significant difference was found in meatiness between the progeny of NN and nn boars. The highest values of the carcass length were found in all groups in the progeny of boars with heterozygote genotype (Nn). The differences in this parameter between this genotype and the other two (NN and nn) were significant.