Abstract: Blends of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with an amino-terminated hyperbranched polymer (HBP) were prepared by a melt-blending method and then characterized by differential scanning calorimetry, rotational rheometer, polarized light microscopy, scanning electron microscope, and tensile and impact tests. The results indicated that the blend containing 1.0 wt % HBP achieved an increase in impact strength by 31.3 % and in elongation at break by 45.5 %. Compared with pure PHBV, the crystallinity of the blend was also reduced from 71.7 % to 59.1 %, whereas the tensile strength almost did not change.