In this study, the effect of two main variables, water source and fish host migration, on the parasite communities of brown trout, Salmo trutta (Linnaeus, 1758), was examined. A comparison of the metazoan parasite communities was carried out among eleven streams flowing into Lake Lucerne in Switzerland. A total of 327 brown trout were sampled during October 2016. Two main hypotheses were evaluated. First, parasite communities would be more diverse in groundwater-fed than in surface water-fed streams because the richer the invertebrate community is in the stream, the easier it will be for a parasite with complex life history to be transmitted and complete its life cycle. Second, parasite communities would be more diverse and abundant in streams with high rates of adult fish migration than in those with low migration.