The crystal modifications and multiple melting behavior of poly(L-lactic acid-co-D-lactic acid) (98/2) as a function of crystallization temperature were studied by wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). It was found that the disorder (alpha') and order (alpha) phases of poly(L-lactic acid) (PLLA) were formed in cold-crystallized poly(L-lactic acid-co-D-lactic acid) samples at low (< 110 degrees C) and high (>= 110 degrees C) temperatures, respectively. A disorder-to-order (alpha'-to-alpha) phase transition occurred during the annealing process of the alpha'-crystal at elevated temperatures, which proceeded quite slowly even at the peak temperature of the exotherm P-exo but much more rapidly at higher temperature close to the melting region. The presence or absence of an additional endothermic peak before the exotherm in the DSC thermograph of the alpha'-crystal was strongly dependent on the heating rate, indicating that a melting process involved during the alpha'-to-alpha phase transition. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 409-413, 2011