Immunocytochemical probes have been used to characterize gap junction distribution in the postnatal ferret trachea by epifluorescence and by laser scanning confocal and electron microscopy. A battery of antibodies directed against fragments of different connexins localized beta 1- and beta 2-gap junction antigens (connexins 32 and 26, respectively) at the intercellular borders of the superficial epithelium while alpha 1-gap junction antigen (connexin 43) was localized to the loose connective tissues. Gap junction labeling in the superficial epithelium declined in the first weeks of life but persisted in the developing submucosal glands to the weanling stage. Localization of the alpha- and beta-antigens was specific for connective tissues and epithelial layers, respectively. These observations suggest that communication competence is an important component of early development in the mammalian airways.