Twenty-five chimeric adult mice were obtained by aggregating 8-cell embryos of or/or and +/+ genotypes (AKR mice), according to the Tarkovsky and Mints method. The coat color and pigmentary epithelium of the eyes were evidence of chimerism. The coat colour of chimeras varied from a small white to a remarkable gray. The weight of the newborn chimeric mice did not differ from normal. The gene or in homozygotes suppressed the retinal anlage. It was noted that variability of the eye size was dependent on the number of or/or cells in the populations that formed the eyes in chimeras or/or in equilibrium AKR. In 18 animals the eye size did not differ from normal. The pigmentary epithelium of the eyes contained from 32 to 40% or or/or cells. Seven chimeras showed microphthalmos. Asymmetric eye abnormality was recorded in three cases. The pigmentary epithelium of such eyes contained from 63 to 84% or or/or cells.