The rheological and mechanical properties of the blends of liquid-crystalline polyester (LCP) and poly(methyl methacrylate) (PMMA) filled with aluminum berate whiskers have been studied.. It was established the combined action of reinforcing LCP and filler onto the property of PMMA matrix leads to marked reinforcing off PMMA. At 10% of filler and 30% of LCP, the tensile strength of PMMA increases by 30% and elasticity modulus by 110%, the processability being no worse. The viscosity of the blend PMMA + 30% LCP + 10% filler practically is the same as the PMMA melt viscosity at 220 degrees C. With increasing concentration of LCP up to 30%, the filler effect in binary matrix becomes more essential. The possible reason is the preferential adsorption of LCP at the filler interface (surface segregation) and additional ordering of LCP near the surface, possible, due to additional stretching of nematic phase in the convergent flow zone. (C) 2000 John Wiley & Sons, Inc.