Previous work has established the pronounced effect of unilateral lid suture during visual immaturity on cell growth in the lateral geniculate nucleus of cats, dogs and monkeys. Most investigators have reported the retinas to be grossly normal but only a few quantitative studies are available and the results are contradictory. We have compared cell section diameters and cell density of parafoveal retinal ganglion cells in the deprived and non-deprived eye of Macaca mulatta after the lids of one eye were studied between the ages of 1-9 weeks for varying periods of time. The results show a decrease in the size and density of parafoveal retinal ganglion cells after long-term (24 months) visual deprivation. Lid suture of lesser duration (2-56 weeks) had no effect on the size of retinal ganglion cells.