Proceeding from the concept of individual radiosensitivity as a sign of total reactivity 3 directions in a study of its possible prediction were considered: establishing correlation between separate indices characterizing the initial state and total radiosensitivity; correlation between body reactions to non-radiation exposures and subsequent irradiation; comparison of total radiosensitivity to irradiation at a small dose and subsequent irradiation at LD50. The following indices were used for the evaluation of the basal status of the body: oxygen consumption level, body mass increase rate, the level of water and basal metabolism, peripheral blood indices, body temperature, basal indices of the functional adrenocortical activity, the state of the cardiovascular system. The following non-radiation stress-exposures were used: physical exercise, constant magnetic field, starvation, hypoxia, and adrenaline administration. A V-type dependency was established for most investigated indices of the basal status and reaction of the body to non-radiation exposures. The utmost radioresistance was shown by animals in whom the basal indices or their reaction to non-radiation exposure approximated the average group level. The third direction: comparison of radiosensitivity and radiation damage--was analyzed by comparing the reaction of cerebral biocurrents to radiation exposure at a small dose with subsequent damage of the body following irradiation at a lethal dose. The accuracy of predicting the outcome of radiation injury by some of the indices varied from 65 to 80%. In some indices of the basal status and reactivity evaluation it reached 85-90%.