In this article we review immunocytochemical localization studies using a monoclonal antibody raised against the 31 kD subunit of bovine H(+)-ATPase, and indirect immunofluorescent staining. In the proximal tubules there is intense H(+)-ATPase staining along the brush borders of S1 and S2, and linear subvillar invagination staining in S1, S2, and S3 segments. In the thick ascending limb of the loop of Henle there is a mild to moderate degree apical cytoplasmic vesicular staining. In distal convoluted tubule there is mild to moderate degree of H(+)-ATPase staining which is sharply delineated along the luminal plasma membrane. In the connecting tubule, the connecting tubule cells show mild to moderate luminal membrane and apical cytoplasmic vesicular staining, and the intercalated cells demonstrate prominent H(+)-ATPase staining which is polarized to either apical or basolateral pole or distributed diffusely throughout the cell. In the cortical collecting duct the principal cells show minimal or no staining while the intercalated cells show very bright H(+)-ATPase staining with 6 identifiable morphologic subtypes based on polarization of the pump to apical or basolateral poles, and the degree of polarization (well polarized or poorly polarized). In the medullary collecting duct the principal cells show no staining and the intercalated cells show prominent H(+)-ATPase staining only in the apical pole. We also describe adaptive responses to different physiologic manipulations e.g., chronic oral acid loads, chronic respiratory acidosis, remnant kidney model, chronic desoxycorticosterone (DOCA) administration, and chronic potassium depletion diet. Moreover, we compare the immunocytochemical localization of the H(+)-ATPase pump of rabbit and kidneys.