Previous research established the influence of strain rate and temperature on the fracture resistance and tensile properties of a wide range of steels. This work demonstrated that the effect of strain rate on the transition from brittle to ductile fracture was extremely sensitive to both the microstructure of the steel and the yield strength. Over the last decade, major changes have been made in steelmaking and processing technology, resulting in the production of much cleaner steels, the inclusion characteristics of which are completely different from the characteristic elongated manganese sulphide predominant in the older type structural steels. The research proposed involves the re-evaluation of the influence of strain rate and temperature on the fracture characteristics of a range of modern structural steels.