Aim The vasorelaxation responses of some peripheral vessels to fenoldopam, a selective dopamine-1 receptor agonist, were observed in N G-nitro-L-arginine (L-NNA), a selective NO synthase antagonist, induced pulmonary artery hypertension (PAH) rats. Methods Rings of rat pulmonary, renal, mesenteric artery were to dopamine-1 (DA 1) receptor agonist responsiveness. All experiments were performed in the presence of indomethacin (10 μmol/L) and propranolol (3 μmol/L) to prevent the production of vasoactive prostanoids and the binding of norepinephrinewith beta receptor. Results It was shown that, during the development of PAH, the vasorelaxation responses to fenoldopam were significantly reduced in peripheral vessels, especially in the pulmonary vessel. After 28days, the Emax (%) in the pulmonary artery was 45.5%±4.1%, being lower than the control group of 97.3%±10.6% and the K A was 2042±221, being lower than the control group of 4272±512 (P<0.01), while in the mesenteric and renal vessels, the vasorelaxation responses were only moderately decreased after 28 days. Conclusion There results show that the detereorated peripheral vessels DA 1 receptor-mediated vasorelaxation might be one of the mechanisms underlying development of hypertension.