The parasitic fauna of freshwater fishes of the Warri River, Delta State, Nigeria, with reference to their prevalence, intensity and differences in metazoan parasites between fish sexes, was investigated. A total of 85 fish samples comprising of 21 Tilapia zillii (Cichlidae: Perciformes), 23 Synodontis clarias (Mochokidae: Siluriformes), 23 Chrysichthys nigrodigitatus (Claroteidae: Siluriformes), 16 Hepsetus odoe (Hepsetidae: Characiformes) and 2 Clarias anguillaris (Clariidae: Siluriformes) collected from the Warri River, Delta State, Nigeria, were subjected to parasitological examination. The overall metazoan parasite prevalence was 32.9%. The metazoan parasites recovered were mainly the acanthocephalans: Neoechinorhynchus prolixum , Pomphorhynchus spp., Acanthocephalus spp. and unidentified acanthocephalan, and nematodes: Camallanus polypteri, Capillaria pterophylli, C. cichlasomae, Procamallanus laeviconchus, Philometroides africanus and Railletnema synodontis. Although the acanthocephalans constituted 75.6% and nematodes 22.2% of the parasites recovered, the nematodes had the highest prevalence (23.5%) compared to the acanthocephalans (9.4%). Similarly, variable prevalences were observed for the other metazoan parasite taxa recovered, namely trematoda; Clinostomum complanatum (1.2%), Leech; Pisciola geometra (2.4%) and Crustaceans (1.2%). The highest parasite prevalence (39.1%) was observed in S. clarias, while the least (23.8%) was observed in T. zillii . Generally, the prevalence of parasites was higher in female (35.7%) than in the males (31.6%), although statistically no significant difference was observed in the prevalence by sex (X 2 = 0.145, P = 0.807). The relatively high overall parasite prevalence in fishes inhabiting the Warri River may be attributed to the relatively high level of pollution.