The work was carried out on 20 lungs collected from donkeys of different age and of both sexes. The study revealed that the cavity of the left atrium of the heart posseses three sinuses. They are arranged according to their topographic position into, left cranial, right cranial and caudal. Each sinus recieves the veins of one or more pulmonary lobe. The left cranial sinus recieves the blood from the left cranial lobe, while the right cranial sinus from the right cranial lobe and the first ventral segment of the right caudal lobe. The caudal sinus recieves blood coming from the remaining part of the right caudal lobe, the accessory lobe and the left caudal lobe. The study provided also that the lobar and segmental branches as well as their further ramifications course along the correspon ding bronchi in all pulmonary lobes except the right and left caudal lobes, where the segmental branches run intersegmentally.