Detailed analyses of the crystallization of polyethylene oxide samples of different molecular weights have been carried out using dilatometry and hot stage polarized light microscopy, in order to establish the dependence of the kinetic parameters on molecular weight distribution.Qualitative molecular weight distributions were determined by turbidimetric titration. In general, crystallization proceeded from randomly nucleated spherulites, the growth rates of which were dependent on the dispersity of the sample, Nucleation was predetermined, but the density varied with the pre-heating temperature as well as with the temperature of crystallization. Very large spherulites were produced if an elevated preheating temperature was used, 80°C and above, due to the low density of nucleation. The data are discussed in the light of the anomalies repeatedly observed in the crystallization isotherms, determined by dilatometry, of polyethylene oxide samples.