Aim: This study investigates the subtypes of the α-adrenoceptor mediating the adrenergically-induced renal vasoconstrictor responses in streptozotocin-induced diabetic and non-diabetic 2-kidney one clip (2K1C) Goldblatt hypertensive rats. Methods: The renal blood flow responses to renal nerve stimulation, noradrenaline, phenylephrine, and methoxamine were measured in the absence and presence of nitrendipine, 5-methylurapidil, chloroethylclonidine and BMY 7378. Results: The renal vasoconstrictor responses were markedly attenuated by nitrendipine and 5-methylurapidil in the diabetic rats (all P<0.05). In the non-diabetic rats, these responses were markedly attenuated by nitrendipine, 5-methylurapidil, and BMY 7378 (all P<0.05). In both experimental groups, chloroethylclonidine markedly accentuated the renal vasoconstrictions caused by all the adrenergic stimuli (all P<0.05). Conclusion: These observations indicate that α1A-adrenoceptor subtypes play a major role in mediating adrenergically-induced renal vasoconstriction in the dia-betic 2K1C Goldblatt hypertensive rats. In the non-diabetic 2KIC Goldblatt hy-pertensive rats, contributions of α1A and α1D-adrenoceptor subtypes were proposed. Apart from post-synaptic α1-adrenoceptors, both in the diabetic and non-diabetic 2K1C Goldblatt hypertensive rats, the potential involvement of presynaptic α1-adrenoceptors is also suggested.