The radioadaptive response and antimutagenic action of lymphoblastoid interferon in the human blood lymphocytes of the children from polluted after Chernobyl accident Bryansk region were studied. Cells pretreated with tritiated thymidine with 2 Gy of gamma-rays at 20 h of culture after PHA-stimulation on seven of the ten donors result in lack of radioadaptive response. On testing some of them (4 donors) no protective adaptive response was found, others (3 donors) pretreated with tritiated thymidine gave sensibilization. Significant decrease in interferon antimutagenic activity in lymphocytes with disturbed adaptive response was also found. It has been proposed that there is similarity or identity of mechanism of radioadaptive response and of non-repair component of interferons antimutagenic action.