Concentrations of heavy metals (Cd, Cu, Cr, Pb and Zn) in tissues of Meretrix meretrix Roding (M. meretrix R.), water and sediments from two estuaries were determined. One estuary is located in an urban area of Kota Kinabalu (Likas estuary) and the other in a rural district of Kota Belud (Kota Belud estuary), where both are in Sabah, North of Borneo island. M. meretrix R. is a kind of mollusk commonly consumed by the inhabitants of many parts of the island. This study indicated that species of mollusk, water and sediment from the urban estuary (Likas) contained higher concentration of some heavy metals than those in rural estuary (Kota Belud). It was found that the mollusk has a potential to be used as bioindicator for the contamination of Cd and Zn in water and sediment of an estuarine environment, as indicated by its high bioconcentration factors (BCFs) values. Overall, this species seemed to accumulate certain metals in its tissue and resisted the entry of others from its surrounding environment. (Contains 1 figure and 7 tables.)