The main results obtained from studying recovery of irradiation embrittlement of reactor vessel steels are presented. Investigations were carried out using WWER-440 vessel materials (base metal, weld metal). The irradiation temperature was 270°C, which corresponded to the operation temperature of the vessel wall. The effect of the annealing temperature and annealing time, neutron fluence, and phosphorus and copper impurity contents on recovery of the ductile-to-brittle transition temperature was studied. Recovery of the transition temperature depends mainly on the annealing temperature. At a phosphorus content exceeding 0.02%, recovery of properties in annealing is complicated. The effect of copper at contents lower than 0.2% has not been observed. At an annealing temperature of 420°C, residual postannealing embrittlement does not depend on neutron fluence. The results obtained in irradiation-annealing-reirradiations are also presented. After annealing, the tendency of the steel to irradiation embrittlement is not increased over that in its initial state.