In order to elucidate the effect of dexamethasone on the expression of transforming growth factor-beta1 (TGF-beta1) in ciliary pigment epithelial (CPE) cells cultured in vitro, rabbit CPE cells were cultured in vitro, treated with DMEM medium containing 0, 1 x 10(-8), 5 x 10(-8), 10 x 10(-8) and 50 x 10(-8) mol/L dexamethasone respectively for 5 days. The TGF-beta1 expression was detected by immunohistochemistry Supervision methods and analyzed semi-quantitatively by HMIAS-2000 image system. As opposed to in vivo, rabbit CPE cells expressed TGF-beta1 under cultured circumstance in vitro. The gray scales of the positive yellow staining in the groups of 1 x 10(-8), 5 x 10(-8), 10 x 10(-8) and 50 x 10(-8) mol/L dexamethasone were 136.57 +/- 4.43, 140.20 +/- 6.10, 142.98 +/- 2.99, 146.80 +/- 1.68 and 150.05 +/- 1.94 respectively. When the concentrations of dexamethasone were equal to or higher than 5 x 10(-8) mol/L and, the expression of TGF-beta1 was inhibited. 10(-7) mol/L dexamethasone showed a significant inhibition. It was suggested that CPE cells possess the potential ability of synthesizing and expressing TGF-beta1. The inhibition of TGF-beta1 expression by dexamethasone may be beneficial to the treatment of proliferative vitroretinopathy, also exert some influence on the secretion of aqueous humor and ciliary inflammation.