Basic fibroblast growth factor (bFGF) and FGF receptors have been localized to photoreceptors and retinal pigmented epithelium (RPE), but the function of bFGF in adult retina and RPE is unknown. Exogenous bFGF has a neuroprotective effect in retina and brain and its expression is increased in some neurons in response to cytokines or stress. In this study, we investigated the effect of light, other types of stress, neurotrophic factors, and cytokines on bFGF levels in cultured human RPE. Some agents that protect photoreceptors from the damaging effects of constant light, including brainderived neurotrophic factor (BDNF), ciliary neurotrophic factor, and interleukin-1 beta, increase bFGF mRNA levels in RPE cells. Intense light and exposure to oxidizing agents also increase bFGF mRNA levels in RPE cells and cycloheximide blocks the increase. An increase in bFGF protein levels was demonstrated by ELISA in RPE cell supernatants after incubation with BDNF or exposure to intense light or oxidizing agents. These data indicate that bFGF is modulated in RPE cells by stress and by agents that provide protection from stress and support the hypothesis that bFGF functions as a survival factor in the outer retina.