The expectorant effect of Ambroxol was observed in 13 cases of respiratory diseases (5 cases with bronchial asthma, 2 cases with acute bronchitis, 2 cases with lung ca, 2 cases with pneumonia, 1 case with chronic bronchitis and 1 cases with pulmonary tuberculosis) between Nov. '83 and Mar. '84. The folliwing results were obtained; 1) Clinical improvement of % of cases after treatment with Ambroxol was 78% of cough, 62% of frequency of sputum expectoration, 59% of amount of sputum vloume, 80% of expectoration and 75% of color of sputum. 2) Clinical improvement of pulmonary function test was as follows;(1) Improvement of less than 10% of FVC was 9 cases(69.2%) improvement between 10% and 20% of FVC was 3 cases(23.1%), and improvement of more than 20% of FVC was 1 case(7.7%). (2) Improvement of less than 10% of FEV₁/FVC was 11 cases(84.6%), improvement between 10% and 20% of FEV₁/FVC was 2 cases(15.4%)3) No remarkable side effects was observed.