The authors created a canine model of severe emphysema using whole lung lavage to deliver repeated porcine pancreatic elastase solution to the terminal airways and alveoli of the right lung. This model produces extreme unilateral panacinar emphysema closely resembling that encountered in patients with alpha1-antitrypsin deficiency. Because the contralateral lung remains functional, the animals can be maintained indefinitely. The model will be of value in developing imaging techniques capable of safely evaluating the effect of treatment on panacinar emphysema in alpha1-antitrypsin-deficient patients.