The aim of this study was to determine whether the flow dynamics and sound spectra of spontaneous cough show characteristic differences in asthma, acute and chronic bronchitis, TBCS and FPD. During the cough, the air flow from the mouth and the sound from the sternal manubrium were simultaneously recorded. The cough sounds were analyzed spectrographically. Peak expiratory flow during cough was significantly lower in asthma than in TBCS, acute bronchitis or FPD. Duration of the first cough sound was longer in asthma than in FPD, TBCS or chronic bronchitis. The number of additional cough sounds was smaller in asthma than in the other conditions. The highest frequency components of cough sound were lower in asthma than in chronic bronchitis or TBCS. The results indicate that pulmonary diseases differ with respect to acoustic and dynamic characteristics of spontaneous cough. This finding may prove useful in the diagnosis of cough.