The density of [3H]dihydroalprenolol binding to beta-adrenergic receptors in the visual structures (visual cortex, superior colliculus and lateral geniculate nucleus) of rats raised under a normal 12 hr light-dark cycle was compared to those of rats visually deprived at different postnatal ages. Unilateral eyelid suture from postnatal days 10 or 16 to 3 months resulted in an increased [3H]dihydroalprenolol bilateral binding in the lateral geniculate nucleus compared to control animals. Monocular deprivation from postnatal days 25, 40, 60 and 90 had no effect on the density of [3H]dihydroalprenolol binding. After re-opening of the eyelid, which was sutured on postnatal day 10, at postnatal day 25 no changes in beta-adrenergic receptor binding in the lateral geniculate nucleus of the adult animal could be detected. After re-opening of the sutured eyelid on day 90, followed by examination of the adrenoceptor density 4 weeks later, the [3H]dihydroalprenolol binding in both lateral geniculate nuclei remained elevated as was also found in corresponding regions of monocular deprived animals. Binocular visual deprivation from postnatal day 10 until the age of 3 months had no effect on [3H]dihydroalprenolol binding in the visual centres in comparison to corresponding control animals. The data suggest that there exists a critical period for the ontogenetic development of beta-adrenergic receptors binding in the visual system of rats during which permanent alterations of receptor binding can be induced by monocular but not binocular visual deprivation.