A biotechnological system for the production of human beta interferon was developed on the basis of a hybrid gene constructed from the coding sequence of the beta interferon gene inserted into the first exon of the sheep beta lactoglobulin gene. It is intended for the expression of human beta interferon in mammary glands of transgenic animals. Two lines of transgenic rabbits were obtained using the hybrid gene. The tissue specificity of the expression of the transgene and the frequency of its inheritance in the first and second generations were studied. The activity of interferon was 2.2 x 10(4)-7.2 x 10(4) IU per milliliter of milk of transgenic female rabbits. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http:// www.maik.ru.