Fibronectin (FN) and hyaluronan (HA) in bronchoalveolar lavage fluid (BALF) and FN released by alveolar macrophages (AM) were examined in 7 nonsmoking healthy control subjects, and 20 smoking patients with chronic obstructive pulmonary diseases (COPD). All patients and subjects were no more than 40 years old. According to the 95% confidence limits of HA and FN in BALF from nonsmoking healthy control subjects, the smoking patients were divided into two groups, those who had HA and FN levels within the limits for nonsmoking controls were classified as the first group (group 1) and those with levels above the control limits were classified as the second group (group 2). Our data showed that the concentrations of HA and FN in BALF and FN released by AM were significantly higher in group 2 than in group 1 patients. There were also significant differences between the two groups in pulmonary function measurements (DLco, FEV1, and FEV1/FVC) which were lower in group 2. HA levels in group 2 patients correlated directly with counts of inflammatory cells in BALF (BALF cells/ml, and numbers/ml of total cells, macrophages, neutrophils and lymphocytes), and the concentration of FN released by AM, and showed an inverse correlation with pulmonary function (DLco and FEV1/FVC). Our results suggest that the inflammatory repair response and fibrosis may play a role in the development of emphysema in young patients with COPD.