The aim of this study was to assess the effect of acute bronchitis and pneumonia on the FEV1 decline rate in a random sample of Cracow inhabitants followed over a 13-year period. A total of 718 males and 1029 females completed the spirometric testing and interview in 13-year follow-up period. Acute chest diseases diagnosed and treated by doctors and reported by respondents in surveys were the source of data on broncho-pulmonary infections. The rate of FEV1 change, expressed in ml per year was estimated for each person in 13-year follow-up period. Persons who reported recurrent bronchitis and pneumonia had significantly lower initial FEV1 levels than those without infections. The effect was controlled for confounders like age, height, smoking and chronic chest symptoms. The initial low ventilatory function by itself was not a predisposing factor for chest infections, unless they were associated with chronic respiratory symptoms. Lung function in men decreased steeply after pneumonia infection, but the effect appeared to be reversible. This effect was not limited to people with pre-existing chronic respiratory disease. The data indicated that in some subjects who reported new symptoms of dyspnea on effort, the acceleration of FEV1 decline due to pneumonia was greater than in people without the symptoms. This may result from the fact that in lower respiratory infection, bacterial or viral agents can produce serious dysfunction of small airways.