The immunohistochemical localization of atrial natriuretic factor (ANF) in the rabbit parotid gland was performed using an antibody against rabbit ANF and avidin-biotin or streptoavidin as detector. Results showed positivity in cuboidal and columnar cells of intralobular ducts and in basal cells of extralobular and main excretory duct. These data support the hypothesis that ANF produced by intralobular ducts could act through a paracrine mechanism; ANF produced by extralobular and main ducts may play a role in the regulation of salivary composition.