EN
Sarcocystosis of wild ducks, relatively common in North America, has hitherto been recorded only three times in Europe. The present study yielded a single case of macroscopically detected sarcocysts in the skeletal muscles of a mallard (Anas platyrhynchos). This finding constitutes the first such record in Poland. A PCR technique was used for identification of the parasite from sarcocysts. The results obtained suggest that the sarcocysts were produced by protozoans, which were the most closely related to Frenkelia glareoli and Sarcocystis neurona (homology of the nucleotide sequences was 96.6% in both cases).