It is widely believed that thoracotomy is necessary to obtain biopsy specimens adequate for the histopathologic demonstration of pulmonary Wegener's granulomatosis (WG). We report five patients with WG who were diagnosed by transbronchial biopsy (TBB). In three cases, a diagnosis of WG was made by TBB alone. In the other two patients, subsequent open lung biopsies confirmed the TBB findings but did not add essential diagnostic information. Our experience suggests TBB may be appropriate as the initial diagnostic procedure in selected cases of suspected WG. This approach requires an understanding of the diverse histologic features of WG and the correlation of clinical and pathologic data. © 1990.