Lysophosphatidic acid (LPA), a naturally occurring glycerophospholipid, can evoke various biological responses, including cell migration, proliferation and survival, via activation of G protein-coupled receptors (GPCRs). However, the role of LPA receptors and details of LPA signaling in migration are largely unexplored. In this study we detect the expression of LPA1 and LPA3 receptors in rat aortic smooth muscle cells (RASMCs). LPA stimulated RASMCs migration in a dose-dependent manner and induced the phosphorylation of p38 mitogen-activated protein kinase (p38MAPK) and extracellular signal-regulated kinase (ERK). LPA-induced cell migration was significantly inhibited by specific LPA1/LPA3-receptor antagonist Dioctylglycerol pyrophosphate (8:0) (DGPP8.0) at higher concentration. Migration of cells toward LPA was partially, but significantly, reduced in the presence of SB-203580, a p38 MAPK inhibitor, but not PD98059, an ERK inhibitor. In addition, pertussis toxin (PTX), a Gi protein inhibitor, induced an inhibitory effect on p38 MAPK, ERK phosphorylation and RASMCs migration. These data suggest that LPA-induced migration is mediated through the Gi-protein-coupled LPA1 receptor involving activation of a PTX-sensitive Gi/p38MAPK pathway.