One of the first questions asked about excavated human skeletal remains is the sex. As the morphological sex determination is complicated in cases involving fragmentary bones and in skeletons from infants and children, the development of DNA-based techniques has led to improvements in sex determination. This study is focused on sex determination from ancient DNA obtained from 25 skeletons found in Middle Aged burials in western Slovakia. We performed separate amplifications of DXZ4 repetitive satellite sequences on the X chromosome, and SRY gene - testis determined factor on the Y chromosome, using nested PCR. Our results showed that DXZ4 was amplified in the case of 23 individuals. With newly designed internal and external primer sets for SRY detection with internal PCR products in lengths of 102 bp and 85 bp we succeeded in detecting the SRY locus in 9 samples. Finally, the gender was determined in 23 individuals (14 females and 9 males). In 20 samples, the gender was determined by morphological and molecular methods. Sex determination of 17 samples using nested PCR matched the morphological one, providing evidence of the authenticity and ancient origin of the PCR amplifications. The DXZ4/SRY nested PCR method represents a useful technique in sex determination of medieval human remains and it is a critical addition to anthropological studies.