To observe the inhibitory effect of triamcinolone acetonide (TA) on the proliferation of monkey choroid- retinal endothelial cells (RF/6A) in hypoxia or normal conditions. · METHODS: TA was added into the cultured RF/6A of rhesus monkey. The effect of TA on the cellular activity was observed by MTT, the effect on cellular proliferation and apoptosis was detected by flow cytometry (FCM). · RESULTS: The numbers of cells in s-phase of a cell cycle were reduced and the proportion of cells in G2-M phase was increased under the hypoxia condition. TA had a great effect on the cell cycle of RF/6A of rhesus monkey and it induced apoptosis of endothelial cells. It relatively increased the s-phase cells and reduced G2-M phase cells under both normal and hypoxia conditions, which indicates its role in blocking cell cycle from s-phase to G2-M phase and reducing mitosis. · CONCLUSION: Hypoxia promotes the proliferation of RF/6A cells while TA has the opposite effect in both normal and hypoxia conditions. TA can also induce apoptosis of endothelial cells.