The crystallization behaviors of poly(p-dioxanone) (PPDO) with different molecular weights (MWs) have been studied using a differential scanning calorimetry. The results showed that the MW of PPDO affects the crystallization rate and crystallinity obviously during the dynamic crystallization process. The Avrami equation has been Used to analyze the overall isothermal crystallization of PPDO. Avrami exponents ranging from 2 to 3 were obtained with good fits (correlation coefficients were greater than 0.999 in all the cases) at T-c ranged from 55 to 75 degrees C. Although no significant influence of MW on Avrami exponent has been found, the MW of PPDO plays dominant role on the rate constant k. The values of k increase with the MW in a T, range from 55 to 75 degrees C. (c) 2006 Wiley Periodicals, Inc.