Heparin was isolated from two bivalve mollusks such as Tridacna maxima and Perna viridis. The isolated heparin was quantifi ed in crude as well as purifi ed samples and they were estimated as 2.72 & 2.2 gm / kg (crude) and 260 & 248 mg/gm (purifi ed) in T. maxima and P. viridis respectively. Both the bivalves shown the anticoagulant activity of the crude and purifi ed sample 20,128 USP units per kg and 7.4 USP units per mg and 39,000 USP units per kg and 75 USP units per mg and 9,460 USP units per kg and 4.3 USP units per mg and 13,392 USP units per kg and 54 USP units per mg correspondingly in T. maxima and P. viridis. The antiproliferative activity was studied with pulmonary artery smooth muscle cells (PASMC) using RPMI media reported that the result in a dose dependent manner. Among the two clams, P. viridis showed more antiproliferative activity than that of T. maxima