Protein metabolism in the body of organism is disturbed by various toxicants like heavy metals, pesticides etc.After chronic exposure to zinc, copper, cadmium and lead for 10 and 20 days, the changes in protein contents were observed in whole soft body tissue of three experimental snail species, Bellamya bengalensis, Mellanoides tuberculata and Lymnaea acuminate collected from Dedargaon reservoir of Dhule district of Maharashtra, India. The results indicates that the protein contents in whole soft body tissues of three experimental snail species were decreased as compared to those of control snails. Among all treated heavy metals, Cd caused more decrease in protein as compared to Zn, Cu and Pb in three snail species. The protein decreased was more after 20 days as compared to 10 days of exposure. A maximum depletion in protein contents were observed in whole soft tissue of Lymnaea acuminata in response to accumulated levels of Zn, Cu and Pb while Mellanoides tuberculata for Cdas compare to studied snail species. Therefore it is concluded that, snail species Lymnaea cuminata is the sentinel organism for biochemical study of heavy metals Zn, Cu and Pb, and Mellanoides tuberculata for Cd in freshwater ecosystem.