The crystallization behaviour of poly(ethylene terephthalate) (PET) and its blends with a liquid crystal polymer (Rodrun 3000) was studied by differential scanning calorimetry (d.s.c.), under both non-isothermal and isothermal conditions. The theories of Ozawa and Avrami were applied to study the kinetics of non-isothermal and isothermal crystallization respectively. In both cases it was found that a very low percentage of a thermotropic Liquid crystal polymer (TLCP) determines an increase in the overall crystallization rate, while increasing the amount of TLCP results in a progressive decrease in the crystallization rate and the melting temperature. However, the crystallinity of PET in the blends was found to increase on increasing the TLCP content.