Vitamin A deficiency (VAD) was induced in male Sprague-Dawley rats by feeding them a vitamin A-deficient diet after weaning and subsequently supplementing their diet with retinoic acid. The serum vitamin A levels of these rats were at a minimum by 60 days of age. Although spermatogenesis can proceed normally during the early phase of vitamin A deficiency, a small number of late spermatids were not released from the seminiferous epithelium at the end of Stage VIII of the cycle of the seminiferous epithelium but rather at a later stage. This observation suggests a delay in spermiation. This delayed spermiation was noted as early as 50 days of age and persisted in rats even after 60 days of vitamin A replacement. These results demonstrate that in rats the timing of spermiation can be retarded by vitamin A deficiency. Although the mechanisms causing this delay in spermiation are not known, the vitamin A-deficient rat provides a useful model system for studies on the regulation of spermiation.