The crystallization behavior of poly(L-lactic acid) was studied in the range of 80-160 degrees C. The peak crystallization time (tau(p)) was defined and obtained from the crystallization isotherm measured with a differential scanning calorimeter (DSC). Isothermal crystallization temperature (T-c) dependence of log(tau(p)) discretely changed at 113 degrees C (= T-b). The linear growth rate of spherulite, G, was measured with a polarizing microscope. The T-c dependence of G and the size of the spherulite also discretely changed at T-b. Crystal structures for samples isothermally crystallized at temperatures which were higher and lower than T-b were orthorhombic (alpha-form) and trigonal (beta-form), respectively. The discrete change of the crystallization behavior was explained by the formation of different crystal. (c) 2006 Elsevier Ltd. All rights reserved.