We investigated the parasite fauna of the Chinese (Amur) sleeper Perccottus glenii Dybowski, 1877 (Perciformes: Odontobutidae) in the Włocławek Reservoir on the lower Vistula River in Poland over 4 yr (2006–2010). Chinese sleeper was unintentionally introduced from eastern Asia to the European part of Russia (near St. Petersburg) in 1916 and has since spread spontaneously throughout Asia and Europe. It is now a frequent component of the ichthyofauna in the Vistula River drainage. In total, 168 seasonally caught individuals of P. glenii were examined for parasites. The parasite community consisted of 18 taxa, including 2 core species, Trichodina domerguei and Nippotaenia mogurndae, and 3 intermediate species, Diplostomum spathaceum (metacercaria [met.]), Echinochasmus spinosus (met.), and Eustrongylides excisus (larvae), with overall prevalence 47.6%, 38.7%, 16.7%, 10.7%, and 12.5%, respectively. Poland is a new locality record for Diplostomum paracaudum (met.), Eustrongylides tubifex (larvae), and Holostephanus luehei (met.). Due to the pathological effects of infection, larvae of Eustrongylides spp. may be a factor that limits Chinese sleeper population growth in the study area.