In this study, helminth parasites in chub of Doganci Dam Lake and seasonal variation of these parasites were investigated monthly from December 1998 to November 1999. A total of 5 species of helminth parasites were found on 29 of 77 fish examined. The following parasites were found: Dactylogyrus folkmanovae, D. vistulae, Paradiplozoon megan, in gills of host fish, and Bothriocephalus acheilognathi, Rhabdochona denudata in intestine of host fish. Dactylogyrus folkmanovae was the dominant parasite species found in chub. The infection was the highest in May during the years of the study. The second dominant parasite, D. vistulae was also the highest in May. The third dominant parasite Rhabdochona denudata was highest during June and November. Paradiplozoon megan and Bothriocephalus acheilognathi were present only in very small numbers. Only three Bothriocephalus acheilognathi were found in the intestine. Occurrence and seasonal variation of the parasite species are discussed.