Immunohistochemistry of 2 cases of familial hyperaldosteronism 3 are described. CYP11B2 is expressed heterogeneously throughout the adrenal. CYP11B2 is co-expressed in cells with KCNJ5 and in many cells with CYP11B1. CYP11B2 is co-expressed in some cells with the 17α-hydroxylase.