Objective：To study the anti-proliferation effects of thiazolidinedione compounds-troglitazone, which is a high affinity ligand of PPAR-γ , on rat pituitary adenoma GH3 cell line and explore the related mechanisms.Methods: GH3 cells were separately treated with troglitazone (10-7,10-6 and 10-5 mol/L), dimethyl sulfoxide (DMSO) (DMSO control group) and phenol red- and serum-free F-12 medium (blank group). MTT was used to examine the cell growth in each group and FACS was used to detect the distribution of cell cycle. Semi-quantitative RT-PCR method was utilized to determine the expression of CyclinD1 mRNA. ANOVA was used for statistical analysis.Results:The 72 h treatment with troglitazone inhibited GH3 cell proliferation in a dose-dependent manner. The treatment also induced cell cycle arrest in G1/S phase and significantly decreased the expression of CyclinD1 mRNA as compared to the other 2 groups (P＜0.05).Conclusion:Troglitazone can obviously inhibit the proliferation of GH3 cells; the molecular mechanism may be the decrease of CyclinD1 mRNA due to binding to PPAR-γ.