Fetal tracheal occlusion (TO) reverses lung hypoplasia by inducing rapid lung growth. Although increases in lung size accompanied by increased numbers of alveoli and capillaries have been reported, effects of TO on lung development have not been formally assessed. In the present study, the objective was to verify our prediction that the main effect of TO would be to accelerate fetal lung development. We have developed and characterized a new fetal mouse model of TO to best realize this goal. At E16.5, pregnant CD1 mice were operated under general anesthesia. One fetus per dam was selected to undergo surgical TO with a surgical clip or a sham operation. The fetuses were delivered 24h or 36h postsurgery. The maturation of lung parenchyma, evaluated by counting the generations of alveolar saccules from the terminal bronchiole to the pleura, was significantly accelerated in the TO group with a complexity of the gas exchange region comparable to postnatal day 1 and 3 after 24h or 36h of TO. Cellular proliferation and apoptosis peaks, assessed by immunohistochemistry directed against PCNA and the active form of caspase-3, were significantly increased 24h after surgery in the TO group compare to the sham group. However, in situ hybridization showed no significant difference in the density of type II pneumocytes expressing SP-C mRNA. Our results show that brief TO during late gestation in fetal mice induces accelerated lung development with minimal effects on SPC mRNA expression.