The aim of this study was to evaluate the effect of artemisinin (ART) on rat vascular smooth muscle cell (VSMC) proliferation induced by tumour necrosis factor (TNF)-α, cell cycle arrest, and apoptosis, and its effect on neointima formation after balloon injury of rat carotid artery. Primary rat VSMC were identified by immunofluorescence assay. The proliferation of VSMC induced by TNF-αwas significantly inhibited by ART treatment in a dose-dependent manner. Treatment with 100-μM ART significantly reduced the expression of proliferating cell nuclear antigen. In contrast, the same treatment arrested the cell cycle in G0/G1 phase. Western blot analysis showed that the cell cycle-related proteins cyclin D1, cyclin E, cyclin-dependent kinase 2, and cyclin-dependent kinase 4 were downregulated by ART in TNF-α-stimulated VSMC. For apoptosis induced by ART, cleaved caspase-3/-9 was detected, and the pro-apoptotic protein Bcl-2-associated X protein was upregulated while the anti-apoptotic protein Bcl-2 was downregulated. The results suggest that ART can effectively inhibit the proliferation of VSMC induced by TNF-αthrough the apoptotic induction pathway and cell cycle arrest. Also, balloon injury indicated that ART significantly inhibited neointima formation in the rat carotid arteries.