Effects of strain rate and temperature on AISI 316L austenitic stainless steel irradiated to a dose of 2.2 displacements per atom (dpa) have been examined. Strain rates ranged between 10^-2 s^-1 and 10² s^-1. Temperatures were ambient and 400°C. Techniques used for preparation of specimens and testing are described together with experimental results. The superposition of the effects of strain rate and irradiation causes important reduction of ductility both at room and at high temperature. Therefore, special cautions should be taken in fixing safety coefficients for the calculation of dynamically loaded structures, such as pressure vessels, in case of an accident in fast breeder reactors.