We localized and characterized angiotensin II receptor subtypes (AT1 and AT2) in the mouse brain, with the use of autoradiography after incubation with [l25I][Sar1]-angiotensin II or [125I]CGP 42112 and displacement with selective angiotensin AT1 (losartan and candesartan) or angiotensin AT2 (CGP 42112(1) and PD 123319(2)) receptor ligands. In the mouse, the receptor subtype affinity for the different ligands was similar to that of the rat. The receptor subtype distribution was also similar to that in the rat, with some notable exceptions, such as the presence of angiotensin AT1 but not AT2 receptors in the locus coeruleus, and the expression of angiotensin AT1 receptors in the caudate putamen. These results confirm that careful consideration of the specific distribution of receptor subtypes in different species, even those closely related such as the mouse and the rat, should be conducted before meaningful comparisons could be proposed. Our data also form the basis for future studies of mouse models such as those with angiotensin receptor gene deficiencies.