Alpha 1-Antitrypsin (alpha 1AT) deficiency is the most common genetic cause of liver disease in children and emphysema in adults. Therapy for pulmonary disease attributable to alpha 1AT deficiency includes alpha 1AT augmentation therapy along with supportive measures. The alpha 1AT preparation that is currently used for therapy is derived from fractionated plasma. The results of clinical trials suggest that augmentation therapy with alpha 1AT slows the progression of emphysema and causes few adverse events. Patients with plasma levels of alpha 1AT that are < 11 mumol/L and who have airway obstruction should be considered for augmentation therapy. Novel approaches include the administration of aerosolised alpha 1AT, recombinant alpha 1AT, gene therapy and synthetic elastase inhibitors.