Clinical studies were made over 7 years on 9 cases to whom long-term chemotherapy with EM was administered for chronic airway infection. 1) Clinical effectiveness: Highly effective in 8 cases; Improvement in QOL was observed in 8 cases. Bacteriological effect: In 7 cases, pathogenic bacteria disappeared. 2) No side effects were observed. 3) Changes in PaO2 levels with the passage of time: In most cases, PaO2 reached a plateau within 1 year. Although in some cases, there was subsequent elevation. 4) The frequency of catching cold over the 7 years period was low with an average of 1.2 times/year per subject. In only 2 cases were subject hospitalized due to acute exacerbation triggered by a cold. 5) Mucociliary transport improved in 7 out of 8 cases examined. However, only 4 of these recovered normal transport. The effect of EM in the other cases in which clinical improvement was not demonstrated was deemed slightly effective. On the basis of the above findings, it was suggested that long-term chemotherapy using EM was clinically efficacious. This is based on the fact that its efficacy, including amelioration of QOL appeared within one year of the initiation of therapy, and continued without decline for over 7 years.