There have been no previous reports of detailed macroscopic findings of the bronchial arteries, the nutrial vessels of the lungs. Also, previously, very little was known about the developmental processes of the bronchial arteries in rats and other laboratory animals. In the present study, we dissected bronchial arteries of adult rats from their origin to the pulmonary hilus, and examined developmental processes of bronchial arteries in a series of rat embryos. We observed one right bronchial artery and one left bronchial artery. The right artery arose from the right highest intercostal artery, ran together with the right vagus nerve along the right side of the trachea and right principal bronchus and reached the pulmonary hilus. The left artery arose from the left internal thoracic artery, ran along the left vagus nerve on the ventral surface of the thoracic aorta, and reached the dorsal surface of the left principal bronchus. In a series of 12 to 20.5-day-old rat embryos, the right bronchial artery was clearly identified in 20.5, 18.5, and 16.5-day-old embryos. In a 15.5-day-old embryo, a vessel corresponding to the right bronchial artery was recognized within the capillary plexus extending along the right lateral surface of the bronchus. In ontogenetic development, there appears to be little difference in completion time of the extrapulmonary part of the bronchial arteries between humans and rats.