We describe a technique of transbronchial biopsy (TBB) in small children, using a plastic suction catheter as the working channel through which biopsy forceps are introduced. An ultrathin (2.2 mm) flexible fiberoptic bronchoscope (FFB) was used to direct the catheter visually into the desired lung segment and to biopsy selectively. This technique was used nine times to obtain biopsy specimens in six different patients, ranging in age from 3 months to 3 and 4/12 years (mean, 19.2 months). Adequate specimens were obtained in eight of nine procedures (89%). Complications included one pneumothorax that did not require evacuation and one episode of sedation-induced hypoventilation that required brief bag-mask ventilation. No significant bleeding occurred. This technique enabled us to obtain lung tissue in infants and small children without resorting to general anesthesia and rigid bronchoscopy.