Austenitic (AISI Types 304, 348, AM-350), ferritic (AISI Type 406), and martensitic (AISI Type 410) stainless steels have been irradiated in aqueous and gaseous environments at several irradiation temperatures to 750 C. Tensile tests were performed at several test temperatures between 20 and 750 C on specimens with integrated neutron exposures to 6.0 x 10²¹ nvt (>1 Mev). The combined effects of irradiation and test temperature produce minimum ductility at intermediate temperatures between 200 and 400 C and at higher temperatures between 600 and 800 C. The significance of these minima with respect to the preirradiation thermal/mechanical treatment, irradiation temperature, neutron fluence, and deformation temperature are discussed. The effects of aging, annealing, recovery, and grain growth are examined. Control tests were performed to determine the effects due to environment alone. Selected parameters such as heat-treatment, cold work, composition, and orientation are considered. Postirradiation annealing studies were performed to determine what portion of the tensile ductility was recoverable after irradiation in significantly different spectra.