Asthma is thought to result from both genetic and environmental influences. The genetic component is most obviously seen in patients who are atopic and have allergic responses to common antigens. We have done lung transplants in two such patients; and we have also transplanted the lungs from two mildly asthmatic patients, whose death was unrelated to their asthma, into two patients with end-stage cystic fibrosis and primary pulmonary hypertension, respectively. The non-asthmatic recipients of asthmatic lungs developed asthma after transplantation; however, the asthmatic recipients of normal lungs have not developed asthma up to three years after transplantation. These observations support the notion that asthma is a "local" disease.