The ryanodine receptor gene (RYR1) and the estrogen receptor gene (ESR) are the best commercially used markers for predisposition of stress susceptibility (malignant hyperthermia ? MH) and increased litter size, respectively. A simplified method of simultaneous detection of MH and ESR genotypes has been developed. The method is based on simultaneous amplification of fragments of two genes by multiplex PCR and subsequent digestion of the products with two restriction enzymes. The PCR and the digestion could be performed in a single tube and all genotypes could be detected by electrophoretic separation on the same agarose gel. Thus, the development of the method can decrease the cost of the sample analysis and increase the speed and efficiency of the analysis. In our study, frequencies of mutated T allele of the RYR1 gene in Large White (LW), White Meaty (WM) and Landrace (L) were 0.11, 0.13, and 0.15, respectively. Frequencies of the preferred B allele of the ESR gene in the same breeds were 0.35, 0.26, and 0.06, respectively.