Transbronchial needle aspiration through a flexible fiberoptic bronchoscope was performed on peripheral lung masses in 42 consecutive patients with bronchogenic carcinoma using a 20-gauge by 1-cm prototype needle. The aspiration was preceded by routine washings and brushings and followed by transbronchial forceps biopsy. Adding transbronchial needle aspiration to the standard combination of transbronchial biopsy, brush, and wash significantly improved the diagnostic yield (48 to 69%, p = 0.046). Considering only lesions 2 cm or greater in diameter, the combination of transbronchial needle aspiration, brush, and wash was superior to transbronchial biopsy, brush, and wash (76 versus 52%, p =0.041). No complications occurred with either transbronchial needle aspiration or transbronchial biopsy, but transbronchial needle aspiration produced less bleeding than did transbronchial biopsy. We conclude that transbronchial needle aspiration of peripheral mass lesions is a safe procedure that can increase the diagnostic yield of flexible fiberoptic bronchoscopy.