Megatrypanum trypanosomes were recovered from the blood of 28 of 66 European bison, Bison bonasus, from Puszcza Białowieska, Poland, during 1986-1988. Seventeen male and 11 female bison, ranging in age from less than 1 year to 21 years, were infected (54.8 and 31.4%, respectively). Of the 17 infected male bison, 9 (ages from less than 1 to 5 years) were infected with 50-200 trypanosomes/ml of blood and showed pathologic changes of the genitalia. The trypanosomes from European bison were compared with Trypanosoma theileri from North American cattle and bison, and T. stefanskii from roe deer in Poland; trypanosomes from European bison were considered to be distinct from the foregoing and the name, Trypanosoma wrublewsku Wladimiroff et Yakimoff, 1909 is hereby resurrected to accommodate this species described by Wrublewskii in 1909 from the same host and geographical locality.