The deformation and fracture behaviour in notched tension of nylon-6/polybutadiene blends is studied as a function of strain rate and temperature. The sensitivity of the fracture behaviour to strain rate and temperature decreases with increasing rubber content. Unmodified nylon-6 can show ductile behaviour below T-g, when the strain rate is sufficiently low. No discontinuous change in fracture energy is observed when passing the T-g of the matrix in the case where the fracture type is already ductile. The fracture energy appeared to decrease with increasing rubber content (tested in tension as well as tested with the Izod impact test) when the fracture type was ductile. In the case of ductile behaviour, fracture is preceded by massive yielding of the entire cross-section of the specimen.