Isolated lung perfusion in the rat is a useful research tool. Pulmonary arteriotomy and venotomy repair is required for animal survival. Rat pulmonary vessels are fragile, thin, and small in caliber, making their repair the focal technical point. This technique has been improved. The arteriotomy now is closed with a single suture and the venotomy no longer requires repair. The lung is returned to its original anatomic position then compressed to stop bleeding. These improvements have improved animal morbidity and mortality markedly while reducing operating time.