Isolated pathogenic bacteria from sputum of the patients with pulmonary emphysema who were admitted in our hospital from 1984 to 1994 were examined to elucidate the relationship between isolated bacteria from sputum and pulmonary functions including vital capacity (VC), forced expiratory volume (FEV1.0), PaO2 and PaCO2. VC of the patients from whom MSSA (methicillin-sensitive Staphylococcus aureus) or Enterococcus faecalis (E. faecalis) were isolated was significantly lower than that of the patients from whom Streptococcus pneumoniae (S. pneumoniae), Branhamella catarrhalis (B. catarrhalis) or Haemophilus influenza (H. influenza) were isolated. FEV1.0 had a similar tendency as VC in terms of isolated organisms from the patients with emphysema. Similarly, PO2 of the patients from whom MSSA or E. cloacae were isolated was significantly lower than that of the patients from whom S. pneumoniae, B. catarrhalis or H. influenzae were isolated, and PCO2 of the patients from whom S. pneumoniae, B. catarrhalis or H. influenza were isolated. There was also impaired respiratory function in the patients from whom MSSA, Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Xanthomonas maltophilia (X. maltophilia) or Enterobacter cloacae (E. cloacae) were isolated, compared with those in the patients from whom S. pneumonia, B. catarrhalis or H. influenzae were isolated. These results suggest that isolated pathogenic bacteria are shifted from S. pneumoniae, B. catarrhalis or H. influenza to MSSA, E. coli, P. aeruginosa, X. maltophilia or E. cloacae in the course of impairment of respiratory function in pulmonary emphysema. The treatment and prophylaxis for acute exacerbation in pulmonary emphysema should be based on these results.