The effect of bronchial brush size on cell recovery during fiberoptic bronchoscopy was investigated. In 20 patients undergoing diagnostic bronchoscopy, 3 additional brushings in normal peripheral airways were performed using sheathed brushes of 1.0, 1.73, and 3.0 mm in diameter. Mean cell recovery was 5.7, 8.1, and 9.0 x 10(4) cells per brush, respectively. There were no significant differences in cell recovery between the 3 brushes. Brush size does not appear to significantly influence cell recovery in normal peripheral airways.