Bioaccumulation of heavy metals in prawns and periwinkles sold at Maciver market in Warri South Local Government Area of Delta State, Nigeria was confirmed by this study. Heavy metals were investigated through standard methods (AOAC, 1984). Results showed that prawn contained lead (3.02 ± 0.02 mg/kg) Chromium (5.64 ± 0.06 mg/kg) and Cadmium (3.18 ± 0.01 mg/k) while periwinkle has the following values Pb (0.012±0.001 mg/kg) Cr (0.03±0.002 mg/kg) Cd (0.003± 0.04 mg/kg). Some of these values were above FAO/WHO standards. There should be regular biomonitoring of aquatic organisms (including shell fishes) and regulating edible food sources to the markets.