It was shown, that tocopherol addition to the incubation medium increased the DNA-polymerase activity of isolated rat liver nuclei. This phenomenon was not discovered in nuclei of vitamin E-depleted rats. The action of tocopherol changed after the extraction of nuclei with triton X-100. In this situation tocopherol decreased DNA-polymerase activity of nuclei. The differences between rates of DNA synthesis was found after simultaneous addition of tocopherol and fraction of tocopherol-binding protein to the nuclei of normal and vitamin E-depleted rats. In this case DNA-polymerase activity of normal nuclei increased, but did not change in nuclei of vitamin E undernourished rats. The difference between them was about 30%. The differences between DNA-polymerase activity of normal and vitamin E-depleted rats after the addition of tocopherol and fraction of tocopherol-binding protein were also found in nuclear matrix preparation. It was supposed that tocopherol was able to take part in functioning of cell nuclei modulating DNA synthesis as well.