The bronchial and vascular patterns of the chicken lung, from specimens age 8–10 days, have been studied by serial, paraffin sections of the whole organ. According to the histological structure, the bronchial system consists of three airway types: primary bronchus or mesobronchus, secondary bronchi, and tertiary bronchi or parabronchi. The mesobronchus gives rise to three sets of secondary bronchi: four dorsomedial, four dorsal, and three lateral ones. The total number of secondary bronchi is 11, which is less than the number reported in adult birds by other authors until now. Nevertheless, the number and distribution of the major vessels, arteries and veins are in basic agreement with previous descriptions.© Willey-Liss, Inc.