α₁-Adrenoceptor subtypes mediating contraction in carotid, aorta, mesenteric and caudal arteries from both Wistar Kyoto (WKY) normotensive and spontaneously hypertensive (SHR) rats were investigated by using the α_1A-adrenoceptor agonist methoxamine and antagonized with selective, competitive antagonists WB-4101, 5-methyl urapidil or BMY 7378 (8-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4,5)decane-7,9-dione dihydrochloride). Isometric tension changes were recorded after methoxamine addition to the arterial rings, and the effects of the antagonists determined. All the antagonists shifted to the right the concentration-response curve to methoxamine. pA₂ values indicate that all arteries but caudal express the α_1D-adrenoceptor subtype, since BMY 7378 values were high in these arteries. Due to the high pA₂ values for 5-methyl urapidil and WB-4101 and the low values for BMY 7378 we conclude that the tail artery expresses the α_1A and not the α_1B subtype. No differences were found between both strains of rats, suggesting that hypertension does not modify the α₁-adrenoceptors in conductance arteries.