Unsaturated biopolyesters, (PHA-DB), obtained from pure anchovy (hamci), hazelnut, soybean oily acids and the mixtures of octanoic acid tin weight ratios of 50/50 and 70/30) were chlorinated up to 54 wt % Cl content. The molecular weights (MW) of the chlorinated biopolyesters were between 1.3 x 10(4) and 3.0 x 10(4) and decreased with the increase in chlorine content in PHA-DB. Melting transitions of the chlorinated biopolyesters were between 62 and 125 degrees C depending on the chlorine content when compared with those of the original PHAs, 44-55 degrees C.