Crustaceans are known intermediate hosts of parasitic infections and also as a source of food borne zoonosis. In recognition of these roles, we undertook a study on the prawn, Macrobrachium vollenhovenii from water systems in the Niger Delta (Ovia River and Warri River) to determine its role as intermediate host of parasitic infections. The prawns were examined for infection from January to December, 2010 and the parasitic form isolated was the metacercaria of a Microphallus sp. Prevalence of the metacercaria in the specimens from Ovia River was 52.3% and 35.4% in those from Warri River. The infection intensity in both river systems was low, 1.2 in Ovia River and 3.0 in specimens from Warri River. The cysts measured 443±50 (378-510) µm × 410±60.7 (336-510) µm. The excysted parasite measured 940±117.6 × 471±44µm, larger than Microphallus bilobatus, the only known species from Africa, which measures 500 × 210µm in size. The parasite under study also differed from M. bilobatus by the possession of lateral folds. The uterus is post-acetabular and located in the intertesticular space bordered posteriorly by the excretory bladder. Infection experiments are needed to determine the identity and definitive host(s) of this parasite.