Both poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are fully biodegradable polyesters. The disadvantages of poor mechanical properties of PLA limit its wide application. Fully biodegradable polymer blends were prepared by blending PLA with PBAT. Crystallization behavior of neat and blended PLA was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray diffraction (WAXD). Experiment results indicated that in comparison with neat PLA, the degree of crystallinity of PLA in various blends all markedly was increased, and the crystallization mechanism almost did not change. The equilibrium melting point of PLA initially decreased with the increase of PBAT content and then increased when PBAT content in the blends was 60 wt % compared to neat PLA. In the case of the isothermal crystallization of neat PLA and its blends at the temperature range of 123-142 degrees C, neat PLA and its blends exhibited bell shape curves for the growth rates, and the maximum crystallization rate of neat PLA and its blends all depended on crystallization temperature and their component. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 3754-3763, 2009