1. In a previous study, we demonstrated phenylephrine-stimulated arachidonic acid (AA) release in rabbit cultured aortic smooth muscle cells. Therefore, we have investigated the functional implications of AA which are involved in the cellular response to phenylephrine, particularly proliferation and migration of rabbit cultured aortic smooth muscle cells. 2. First, to determine whether AA directly modifies proliferation and mobility of vascular smooth muscle cells (VSMCs), we exposed the cells to AA. AA induced proliferation and migration of the cells in a dose-dependent fashion. Concomitantly added catalase inhibited the proliferation and chemotaxis induced by AA of VSMCs. Conversely, aminotriazole enhanced the proliferation and migration induced by AA. 3. Secondly, we investigated whether the proliferation and migration of VSMCs by phenylephrine were related to AA and hydrogen peroxide (H2O2). The proliferation and chemotaxis of VSMCs by phenylephrine were inhibited by a phospholipase A2 (PLA2) inhibitor, or catalase. 4. Lastly, we investigated the effects of AA and phenylephrine on the content of H2O2 in VSMCs. AA and phenylephrine treatment led to an increase of H2O2 in a dose-dependent manner. 5. These results suggest that the addition of phenylephrine to the cells caused the enhancement of proliferation and migration, probably by mediating AA release and reactive oxygen species (ROS) production.