Objective: To investigate the effects of endothlin- 1 (ET- 1 ) on vascular smooth muscle cells(VSMCs ) proliferation and the expression of Peroxisome proliferator-activated receptorγ (PPAR-γ) in VSMCs. Methods: VSMCs of 16-week-old wistar rats thoracic aorta were cultured. VSMCs were treated by ET-1 for 48 h and observed of the proliferation by MTT. The expression of PPAR-γmRNA and protein in cultured VSMCs treated by different concentration of ET-1 for 48 h was detected by RT-PCR and Western blot.Results: Compared with control group, VSMCs treated by ET-1 proliferated with the increase concentration of ET-1. There was significant differences among different groups ( P ＜ 0.01). Meanwhile, the expression of PPAR-γ both in mRNA and in protein levels deceased. The expression of PPAR-γ in VSMCs was gradually decreased along with the increase concentration of ET-1. There was significant differences among different groups ( P ＜0.01). Compared with control group, the expression of both PPAR-γ mRNA and PPAR-γ in ET-1 treated groups were lower( P ＜ 0.01). Conclusion: ET-1 could induce VSMCs proliferation and the expression of PPAR-γ in VSMCs, which demonstrates that high dose ET-1 obviously weakens the function of PPAR-γ to increase VSMCs proliferation.