[en] The heads of rats were protected by lead shields. The midline tissue dose behind the shield was approximately 40 percent of the midline tissue dose at the same point without shield in place. The experiments were done in two parts: (1) The protective effect of head shielding on the incapacitation of general performance capacity postexposure was observed by rotarod method. Head shielding shortened significantly the early temporary incapacitation and postponed strikingly the onset time of permanent incapacitation after 300 Gy and 400 Gy irradiation; and decreased the incidence of frantic activity markedly after 400 Gy irradiation. (2) The protective effect of head shielding on the incapacitation of higher nervous system activity postexposure was observed by maze method. Head shielding alleviated significantly the decrease of avoidence and correct reaction, the prolongation of the reaction time and the degree of error after 200 Gy and 100 Gy irradiation