Angiotensin II (A II) binding activity was detected in the particulate fraction (100,000 g, 60 min precipitate) of cultured porcine aortic endothelial cells. Scatchard analysis of the binding activity indicated a single class of binding sites with a dissociation constant (Kd) of 1.1 nM and a total binding capacity (Bmax) of 125 fmol/mg protein. The binding of [125I]A II was inhibited by excess unlabelled A II, A II analogues ([Sar1, Ile8]A II and [Sar1, Ala8]A II), A I (angiotensin I) and A III (angiotensin III), but not by bradykinin. Type specific A II receptor antagonists, losartan (type 1 angiotensin II receptor) and PD123319 (type 2 angiotensin II receptor), did not inhibit the binding. These results suggest that the A II specific binding protein(s) or receptor(s) is present in arterial endothelial cells, and that it is different from typical type 1 and type 2 angiotensin II receptors.