[en] Experiments were performed in order to test the hypothesis of a correlation between ionizing radiation and DNA repair inhibition under in vivo conditions. In a biometrically planned dominant lethal test on mice, the repair inhibition on the male gametes by butazolidine, TWEEN 80 and vitamin A was studied after gamma irradiation at 20 rad/10 min. No effect was observed in the case of butazolidine and TWEEN 80, whereas the influence of a high concentration of vitamin A (1 million IE/kg) was just at the statistical significancy threshold. (G.G.)