From 1976 to 1987 alpha 1-antitrypsine deficiency type PiZZ was diagnosed in 89 patients living in the Copenhagen urban area (mean age: 45 years). Spirometry was performed yearly in 66 of these patients (mean observation period was 50 months). At the time of diagnosis basic FEV1 was significantly lower in smokers and ex-smokers than in patients who had never smoked (45%, 44% and 84% of predicted normal, respectively). However, the decline in FEV1 was similar (3% per year) in all three categories of smokers. Our results indicate that both smokers and non-smokers are at risk of developing pulmonary emphysema, however, the disease usually appears later in life or not at all in non smokers.