We examined the gene expression of angiotensin AT1A receptors in aortic endothelial cells of cyclosporine induced hypertensive rats using reverse transcribed polymerase chain reaction method. The gene expression of angiotensin AT1A receptors in aortic endothelial cells of cyclosporine induced hypertensive rats showed a two-fold increase when compared with that in normotensive control rats. These results raise a possibility that the up-regulation of endothelial angiotensin AT1A receptors participates in the pathogenesis of cyclosporine induced hypertension.