- In a retrospective study of thirty-one immunosuppressed patients with new pulmonary infiltrates transbronchial biopsy provided a specific diagnosis in 11 of the 31 (36%) patients. In a further five patients, whose biopsy showed non-specific interstitial pneumonitis, a specific diagnosis was established by other means. Overall a specific diagnosis was obtained in 52% of patients. Twelve patients were left with a diagnosis of non-specific interstitial pneumonitis. In three out of 31 (10%) patients insufficient tissue was obtained. The seven patients who had metastatic carcinoma of the lung did poorly. The nine with other specific diagnoses did better in that five of them were alive after more than 11 months of follow-up. Patients with non-specific pneumonitis did well; eight out of 12 (67%) were alive after an average follow-up of 13.4 months. In 27 of the 31 (87%) patients the procedure was felt to have influenced therapeutic decisions. This was true whether the biopsy yielded a specific or a non-specific diagnosis. In our series making a specific diagnosis did not improve the patients' survival. Those with non-specific pneumonitis who were treated empirically did well, as did patients with specific diagnoses other than metastatic carcinoma of the lung.