Objective To investigate the regulative characterisitics of growth factors on proliferation of retinal pigment epithelial (RPE) cells in vitro. Methods Primary culture and subculture of RPE cells were establised in vitro Tumor.necrosis factor-alpha;(TNF-alpha;),interleukin-1beta;(IL-1beta;) and basic fibroblast growth factor (bFGF) in different concentrations were added to the RPE cells.3 H-thymidine(3 H-TdR) incorporation and a hemocytometer measured DNA synthesis and cell number separately. Results After RPE cells were separately treated with TNF-alpha;,IL-1beta; and bFGF,DNA synthesis was increased by 2.74,2.66 and 1.69 folds and cell number was increased by 54%,22% and 7amp; (Plt;0.05) respectively. When two growth factors were combined (TNF-alpha;+bFGF, IL-1beta;+bFGF),3.14,2.84 and 2.57 folds increased DNA synthesis significantly in each group (Plt;0.05). Compared with value by effect of two growth factors,the combination effect of three growth factors (TNF-alpha;+IL-1beta;+bFGF) was still ber (Plt;0.05). Conclusion The synergism of growth factors in their action might be one of the important roles in modulating the proliferation of RPE cells. (Chin J Ocul Fundus Dis,1998,14:95-97)