Fresh water edible crab, Barytelphusa guerini were exposed to acute dose of mercury chloride and copper sulphate. The aim of investigation was to evaluate the effect of heavy metal on the enzyme secretary activity in hepatopancreas of B. guerini. The effects were studied and observed seasonally into two groups as control and experimental. The experimental groups were exposed to HgCl2 and CuSO4 at different concentration as for 24, 48, 72 and 96 hrs. At the end of 96hrs the crabs were removed and hepatopancreatic tissue was separated and enzyme extract was prepared for assay purpose. The results are reported in mg of maltose/gm of tissue/hr. In the present investigation, the amylase was significantly altered and progressive decrease in amylase activity was observed due to inhibitory action of HgCl2 and CuSO4. Among the exposed mercuric chloride was found to be the potent inhibitors of amylase activity as compared to control and copper sulphate. From the results, it is also observed that the enzyme activity is time dependent.