In a light microscopic study of retinal whole mounts, we quantified the topographical distribution of rod and cone photoreceptors in the domestic pig (Sus scrofa). The retina's highest cone density (19 000 to 24 000/square mm) is found above the optic disc, in a broad band slightly below and to the temporal side of the eye's centre. High cone densities averaging 15 000 to 16 000/square mm extend above this broad band and outwards to the mid-periphery. There is less than a four-fold decrease in cone density between the centre and outer edge of the periphery. Photoreceptor density decreases in proportion to distance from the centre and conversely, rod frequency increases from an average of 84% in the area of the broad band to 86% to 92% in the far periphery. Taken together, these data indicate that photoreceptor cell distribution is relatively homogeneous in the porcine retina, with the overall ratio of rods to cones at 8:1. In light of the most recent theories to explain human degenerative eye disease, these features of the pig retina make it the most favourable model for therapeutic research into the mechanisms of photoreceptor death in patients with hereditary retinal degeneration.