Corneal endothelium is a target tissue for retinoids and epidermal growth factor (EGF). We report here that retinoic acid and its synthetic analog, CBS-211 A (10(-8)-10(-7) M), enhance the mitogenic effect of EGF on cultured bovine corneal endothelial cells (BCEC). Furthermore, retinoid treatment increases the EGF-binding capacity of BCEC. The addition of cycloheximide (0.5 micrograms/ml) to cultures simultaneously with retinoids suppressed the retinoid effect on EGF-binding. These results suggest that retinoids could induce the expression of EGF receptors on BCEC as an early event. This study demonstrates a cooperation between retinoids and EGF in corneal endothelium and suggests that retinoids could have a beneficial effect on this tissue repair in vivo.