In a longitudinal clinical study, two hundred subjects have been evaluated in order to identify alpha 1-antitrypsin deficiency patients. According to their serum alpha 1-antitrypsin levels, they have been divided into three groups: 25 patients with severe deficiency (with both pathological alleles--ZZ, SZ or Z and rare deficiency allele--and, if clinically suggested, to be treated with augmentation therapy), 92 patients with intermediate deficiency (with one pathological allele, to be followed up in order to evaluate the risk to develop deficiency related disease) and 63 healthy subjects (normal alleles MM). They performed lung function test (including cardiopulmonary exercise test and methacholine bronchial challenge) chest X-ray and high resolution computed tomography, blood tests. Severe deficiency patients also performed perfusional lung scan to detect early disorders of blood flow, evaluation of arterial blood gases and liver echotomography. Expiratory flow limitation, the prevalence of vascular disease, the amount of urine elastin products and correlations between the amount of nitric oxide exhaled and bronchial hyperresponsiveness have been also investigated. The study showed that in Brescia county the deficiency is more common than expected and that evaluation of liver and vessels might be as useful as lung function tests. In addition, beneficial effect on local system has been observed. The longitudinal study might permit to detect early organ damage and to eliminate additive risk factors.