Objective: To investigate the effects of Rho-associated coiled-coil containing protein kinase I/II (ROCK I/II) on migration and proliferation in human aortic vascular smooth muscle cells (HA-VSMCs) induced by transforming growth factor β1 (TGF-β1). Methods: The protein expressions of ROCK I and ROCK II among HA-VSMCs respectively treated with ROCK I siRNA transfection, ROCK II siRNA transfection, TGF-β1 alone, and ROCK I siRNA or ROCK II siRNA transfection plus TGF-β1 were compared. The migration and proliferation abilities among HA-VSMCs respectively treated with TGF-β1 alone, ROCK I siRNA or ROCK II siRNA transfection plus TGF-β1, and ROCK I inhibitor Y-27632 plus TGF-β1 were compared. Untreated HA-VSMCs were used as blank control for all experiments. Results: Compared with blank control HA-VSMCs, the ROCK I protein expression was significantly increased (P<0.05) but ROCK II protein expression was unchanged (P>0.05) in HA-VSMCs after TGF-β1 alone treatment, the corresponding target protein expression was significantly decreased in HA-VSMCs after ROCK I siRNA or ROCK II siRNA transfection (both P<0.05), and the increased ROCK I protein expression in HA-VSMCs induced by TGF-β1 was significantly inhibited by ROCK I siRNA transfection (P<0.05). Compared with blank control HA-VSMCs, the number of migrating cells in HA-VSMCs after TGF-β1 alone treatment was significantly increased (P<0.05), and this effect was significantly inhibited by ROCK I siRNA transfection or Y-27632 pretreatment (both P<0.05), but was not influenced by ROCK II siRNA transfection (P>0.05); the proliferation in HA-VSMCs was significantly enhanced by TGF-β1 alone treatment, and the TGF-β1-induced proliferation was not affected by either ROCK I siRNA, ROCK II siRNA transfection or Y-27632 pretreatment (all P>0.05). Conclusion: ROCK I may play a major role in TGF-β1-induced migration of HA-VSMCs, but either ROCK I or ROCK II may not participate in TGF-β1-induced proliferation of HA-VSMCs.