The studies undertaken were aimed at detecting the biological effects of radioactive radiation on rat's organism, through studying the activity of lysosomal enzymes in both blood plasma and some organs. The contemporary studies suggest that lysosomes play an important role in the occurrence and course of postradiation disease. The obtained results suggest the multidirectional gamma-rays effects on lysosomal enzymes response in serum, leucocytes, liver lysosomes and in liver, kidneys, lungs, heart. Increased activity of acid phosphatase, beta-glucuronidase and beta-acetyl-glucosaminase in the tissues of irradiated animals indicates that gamma rays labiliza the lysosomal membrane. The range of changes indicates a selective nature of this phenomenon. Kidneys, lungs and liver appeared the most ray--sensitive organs. The activity of acid phosphatase was found to be most increased in blood serum and leucocytes. The activity of all the examined enzymes in liver lysosomes was decreased. Acid phosphatase exhibited the greatest activity increases. Lysosomal responses, as one of the radiobiological effects of postradiation disease are indicative of the degree of destructive or regenerative changes in the organism.