Objective: To evaluate cyclooxygenase-2 (COX-2) expression induced by insulin in cultured rat vascular muscle smooth cells (VSMCs). Methods: The rat VSMCs were isolated and cultured in 60 mm plates, pre-treated with insulin 10, 100, 500, 1 000 mU/L for 6 h, and 100 mU/L for 3, 6, 12, and 24 h, respectively. RT-PCR was performed to measure COX-2 mRNA induction, and Western-blot was used to measure protein expression. In regard to the COX-2 enzyme activity, after stimulation for a specified duration, the culture medium was collected; Prostaglandin E2 (PGE2) released by VSMCs was measured with an EIA kit. Results: Three hours after insulin (100 mU/L) stimulation, the induction of COX-2 mRNA was detectable and increased with the time and dosage of insulin. Insulin induced COX-2 protein expression occurred in a time- and dose-dependent manner. In rat VSMCs, COX-2 induced by insulin resulted in PGE2 production, which was increased with insulin action. Conclusion: Insulin could induce COX-2 expression and PGE2 Methods: The rat VSMCs were isolated and cultured in 60 mm plates, pre-treated with insulin 10, 100, RT-PCR was performed to measure COX-2 mRNA induction, and Western-blot was used to measure Protein expression. In regard to the COX-2 enzyme activity, after stimulation for a specified duration, the culture medium was collected; Prostaglandin E2 (PGE2) released by VSMCs was measured with an EIA kit. Results: Three hours after insulin / L) stimulation, the induction of COX-2 mRNA was detectable and increased with the time and dosage of insulin. Insulin induced COX-2 protein expression occurred in a time- and dose-dependent manner. In rat VSMCs, COX-2 induced by insulin resulted in PGE2 production, which was increased with insulin action. Conclusion: Insulin could induce COX-2 e xpression and PGE2