Blends of nylon-6 with polybutadiene were prepared with comparable morphology and different molecular weights of the matrix. These specimens were tested using the notched Izod impact test and the notched tensile impact test. An increase in molecular weight resulted in a shift of the brittle-to-tough transition temperature of 40 degrees C to lower temperatures. In the notched tensile impact tests, especially in the high-speed region, pronounced differences between blends with different molecular weights of the matrix were observed.