Alpha1-antitrypsin (AAT) deficiency is an underrecognized inherited disorder with pulmonary and hepatic implications for both adults and neonates. Clinical expressions of AAT deficiency are seen in the lung, liver, and the skin, with considerable variability in the severity of clinical disease. AAT deficiency accounts for nearly 3% of all cases of chronic obstructive pulmonary disease and is responsible for early-onset emphysema in nonsmokers. Ten to twenty percent of affected neonates develop significant liver disease. Panniculitis, a rare skin complication of AAT deficiency, is characterized by acute inflammatory infiltrate and fat necrosis. While we concentrate on the pulmonary aspect of AAT deficiency, we have included discussion of liver disease and panniculitis. Critical care and advanced practice nurses will benefit from gaining a better understanding of the causes, pathophysiology, diagnosis, and treatment of this disorder.