The study of a biological effect of ultraviolet, ultrahigh frequency and gamma-radiation, as well as combinations of these, on the functional status of the sheep body systems has made it possible to evaluate the sensitivity of a body exposed to these factors and its adaptive potentials. The pattern of variations in the body systems when a combined EMR is applied depends on to which extent one or another factor dominates the others. It is however possible that the effect of the leading factor is modified by that of a less severe radiation, energy characteristics of which differ from those of the dominating factor.