This work was designed to explore the role of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway in migration of bronchial smooth muscle cells (BSMCs) of chronic asthmatic rats. To make chronic asthma model, Wistar rats underwent ovabumin (OVA) injection and eight-week inhalation. BSMCs were cultured in vitro. The expression of ERK1/2 in BSMCs was analyzed by immunocytochemistry, Western blot and RT-PCR. Migration of BSMCs was detected by both plate test and Boyden cell test. Results showed: (1) With Western blot technique, the ratio of p-ERK1/2 to total ERK1/2 in chronic asthmatic group was obviously higher than that in the control group (0.55 +/- 0.05 vs 0.48 +/- 0.04, n=10, P<0.01). (2) With RT-PCR, the relative A values of ERK1 and ERK2 mRNA in airways of chronic asthmatic rats were 1.83 +/- 0.24 and 1.07 +/- 0.11, respectively, which were significantly increased compared with that in the control group (0.58 +/- 0.14 and 0.51 +/- 0.12, n=10, P<0.01). (3) In plate test, the migration of BSMCs of chronic asthmatic rats was 2.9 times of that in the control group and reached 5.0 times by epidermal growth factor (EGF) stimulation, but decreased to 1.7 times by 30 mumol/L PD98059. (4) In Boyden cell test, the migration of BSMCs of chronic asthmatic rats was 1.9 times of that in the control group, and reached 3.1 times by EGF stimulation, but decreased to 1.45 times by 30 mumol/L PD98059. Our results indicate that the migration ability of BSMCs of chronic asthmatic rats increases, and ERK1/2 signaling pathway may play an important role in this process.