Blends of liquid crystalline polymer and engineering plastic, PBT, were prepared for the application of molecular composite concept. Thermal, morphological and mechanical properties were examined by differential scanning calorimetry, optical microscopy, scanning electron microscopy and tensile test. In the blends, liquid crystalline phase did not reveal any significant macrophase separation and thermal degradation under the temperature of processing condition, but macrophase separation was observed at higher temperature. Crystallization kinetics of the blends were investigated by the isothermal DSC method. Th Avrami analyses were applied to obtain the information on the crystal growth geometry and fctors controlling the rate of crystallization. By scanning electron micrographs of cryogenic fracture surfaces of extruded fibers, the LCP domains were found to be finely and uniformly dispersed in 0.1 to 0.3 μm size. Interfacial adhesion between the LCP and matrix polymer was rather poor. Under certain condition LCP formed a fiber structure in the thermoplastic matrix, with thin oriented LCP fibrils in the skin region and spherical or ellipsoidal LCP domains in the core. Tensile strength and modulus of the blend fiber containing 20% LCP measured at room temperature were 63 MPa and 2.40 GPa, respectively, which are relatively higher than those of pure PBT.