A QPCR analysis of androgen receptor and several androgen metabolizing genes was performed during the saccular and alveolar stages of mouse lung development. Androgen receptor expression showed a statistically significant increase during the alveolar stage while levels of 17beta-hydroxysteroid dehydrogenase type 2 (17beta-HSD 2) expression significantly decreased at the end of the saccular stage and remained low throughout the alveolar period. 17beta-HSD 1, 17beta-HSD 5, 5alpha-reductase type 1, and mouse 3alpha-HSD did not present such a regulation. The androgen receptor protein was primarily detected in the nucleus of airway epithelial cells and of a subset of respiratory epithelial cells. 17beta-HSD 2 mRNA co-localized with androgen receptor protein during saccularization, but was absent from airway epithelium during alveolarization. Taken together, our results demonstrate temporal and spatial regulation of androgen receptor and 17beta-HSD 2 during the sacculo-alveolar transition period of mouse lung development suggesting control of androgen action.