Age-related changes in the outer retina of Japanese quail 3 months to 3 years of age have been assessed with light and electron microscopy. A major difference was observed between males and females in the accumulation of lipofuscin in retinal pigment epithelial (RPE) cells. Females showed greater densities of lipofuscin granules, larger granules, and more lipofuscin per RPE cell than did males of comparable ages. In addition, a small but significant decrease (14-16%) in photoreceptor nuclear densities occurred in the temporal retina of both 1-year females and 3-year males. An overall correlation of -.77 between photoreceptor densities and amount of lipofuscin was observed, with a correlation of -.88 for females, alone. No male/female differences were observed with regard to age-related changes in height of RPE cells. Major differences in calcium metabolism and demand associated with egg-laying in females may underlie the observed sex-related differences that occur in the outer retina of this relatively short-lived, domestic species.