Heavy metals and some organic substances which are drained into the aquatic environments and cannot be decomposed or eliminated will sink into sediments or find their way into different levels of food chain. Bioaccumulation is the process of continuous deposition and aggregation of these substances into the body tissue of living organisms. Mollusks are remarkably appropriate to be used as bio-indicators because of their motionless or almost sessile nature, relatively high abundance, selective absorption of certain ions, and worldwide distribution in marine and inland aquatic habitats. Chiton lamyi is a sedentary species from the phylum, Polyplacophora, which is usually abundant on the rocky shores and intertidal zone of marine environments. Sediment and Chiton samples were taken from four stations of Chabahar Bay in autumn 2013. After acid digestion of samples, the concentration of heavy metals (mercury, cadmium, arsenic, nickel, lead and copper) were measured by the graphite furnace atomic absorption apparatus, and the bioaccumulation factor in relation to sediment was calculated. The highest concentration value was calculated as 3.28 for cadmium in the Hafte Tir station. The results of this study indicated that chitons can be used as an appropriate bio-indicator for heavy metals particularly cadmium pollution in the marine environment.