In an attempt to reassess the accuracy of the roentgenologic diagnosis of chronic bronchitis, we have studied the chest radiographs of approximately 300 men comprising roughly equal numbers of normal subjects and patients with chronic obstructive pulmonary disease (COPD). Emphasis has been placed on the thickness of bronchial walls visualized end-on in the parahilar zones, identified in roughly 80% of both groups. Step-wise discriminant analysis of six variables showed that the median estimate of bronchial wall thickness was of some value in discrimination.