Estuaries are being polluted by a variety of persistent toxic substances (PTSs) such as pesticides, heavy metals and organotins. Bivalve molluscs are known as biomarkers of estuarine pollution, since they store and concentrate such toxic substances in their vital body tissues. More recently, changes in metabolites and enzymes are being employed as biomarkers in the evaluation of toxicological studies. Variations in acid and alkaline phosphatases activity in the digestive gland of the edible clam, Anadara rhombea under sublethal concentrations (10%, 20% and 30% of Lc50 value) of Tributylin chloride (TBTCL) over a period of 15 days were studied in the laboratory conditions. There were increases in the levels of both phosphatases activity in the digestive gland of A.rhombea with increase in the concentration of TBTCL and time of exposures. Significant differences (p<0.05) were noticed in the treated clams. The increase was associated with the decrease in stability of digestive gland lysosomal membrane or with digestive gland damage which reflects proliferation of lysosome in attempt to sequester the toxic organotin, TBTCL.