Erythema, oedema, secretion and friability of the mucosa are the findings of inflammation and may well be assessed visually by fiberoptic bronchoscopy (FOB). We aimed to investigate the correlation of inflammatory changes on bronchial mucosa with the smoking history, spirometric test results and arterial blood gas analysis. We evaluated ninety-four patients undergoing fiberoptic bronchoscopy for miscellaneous indications of inflammatory changes in bronhial mucosa due to chronic bronchitis. The erythema, oedema, secretions and the friability of the bronchial mucosa were scored from 0 to 3 for every lobar bronchus. The sum of the scores for a patient was designated as chronic bronchitis index (CBI). The patients were allocated into two groups according to whether they had (Group I) or did not have (Group II) symptoms of chronic bronchitis. CBI in Group I was significantly higher than that of Group II (23.8±10.1 v.s. 17.9±8.2, p=0.0025). The higher the CBI, the higher the PaCO2 was and the lower the spirometric test results, PaO2 and O2 saturation were. However, only two of the parameters, namely MMF and PaO2 showed a significant negative correlation with CBI (r=-0.274, p=0.04; r=-0.221, p=0.04 respectively).