Variations in the helminth species parasitizing the rudd, Scardinius erythrophthalmus L., and their prevalences were compared in 2 different localities (Golbasi Dam Lake and Kocadere Stream) in Bursa province in northwestern Turkey. The overall prevalences of helminth infections were 46.7% and 92.3% at Golbasi Lake and Kocadere Stream, respectively. The following helminths were detected: Dactylogyrus difformis, Diplostomum spathaceum metacercariae, Asymphlodora markewitschi, Ligula intestinalis plerocercoids, Skrajibillanus scardinii, Eustrongylides sp. larvae, and Hysterothylacium sp. larvae. Among these species, D. difformis and D. spathaceum were recorded at both sampling stations. However, D. difformis was the dominant species in rudd in Golbasi Lake (overall prevalence 40%) while D. spathaceum was prevalent in Kocadere Stream ( overall prevalence 80.7%). L. intestinalis plerocercoids were present only in Golbasi Lake, while S. scardinii, A. markewitschi, Eustrongylides sp. larvae, and Hysterothylacium sp. were detected only in Kocadere Stream. It is concluded that within the same fish species the distribution of helminths and their prevalence vary substantially, especially for some parasites, between 2 different habitats ( lake and stream).