Levels of Cu, Zn, Cd, Pb and Ni in shrimps and crabs from Thane-Bassein creek system, Maharashtra, India were evaluated for a period of one year and reported as baseline for future monitoring of this vital ecosystem. The pattern of concentration was in the order of Zn>Cu>Cd>Ni>Pb. In shrimps maximum level of Cu (av. 41.3 ppm dry wt) and Zn (av. 164 ppm dry wt) were observed respectively in Metapenaeus brevicornis from Thane Creek and Exopalaemon stylifera from Bassein Creek. The crabs, Scylla serrata from Thane Creek showed maximum concentration for Cu (73 ppm dry wt) and Zn (376 ppm dry wt). Cd, Pb and Ni contributed very little to the percentage contribution of the metals estimated. In general the concentration of metals in shrimps and crabs were 2-11 times higher than that reported for Bombay harbour. However, the levels of these metals have not exceeded the limit prescribed for consumption.