A method allowing simultaneous genotyping of two loci: ryanodine receptor 1 (RYR1) and estrogen receptor (ESR) is presented. In multiplex PCR amplification, two amplicons were simultaneously produced: a 272 bp fragment of RYR1 gene and a 185 bp fragment of ESR gene and were then subjected to "one-tube" restriction enzyme digestion with Hin6 I and Ava I, respectively. A total of 122 Polish Large White and Polish Landrace pigs were genotyped by this method, demonstrating its reliability, convenience and lower costs. This method may be useful in the wide-scale genotyping of both loci in pig breeding programmes.