To investigate the value of computed tomography (CT) for depicting the relationship between carcinomatous solitary pulmonary nodules and the bronchial tree and predicting the results of various bronchoscopic biopsy techniques, the authors retrospectively reviewed CT scans from 27 consecutive patients with solitary pulmonary nodules associated with a positive bronchus sign. All patients underwent bronchoscopy and transbronchial biopsy. Macroscopic demonstration of the tumor-bronchi relationship was obtained in 18 patients. Five basic types of tumor-bronchus relationships were identified with CT: (a) bronchus cut off by the tumor, (b) bronchus contained within the tumor, (c) bronchus compressed by the tumor, (d) thickening and smooth narrowing of the bronchus leading to the tumor, and (e) thickening and irregular narrowing of the bronchus leading to the tumor. The diagnostic yield of transbronchial forceps biopsy and bronchial brushing was significantly higher in nodules characterized by a cut-off or contained bronchus. Transbronchial needle aspiration was performed in six patients, and results were positive in five, all of whom had a compressed or thickened bronchus. These results confirm that yield of transbronchial biopsy is determined by the type of tumor-bronchus relationship and the biopsy technique performed.