The value of transbronchial biopsy and bronchoalveolar lavage was assessed in the diagnosis of pulmonary disease in patients infected with the human immunodeficiency virus (HIV). Seventy four transbronchial biopsy and 66 bronchoalveolar lavage specimens (60 paired specimens) from 80 examinations in 64 patients were reviewed. Pneumocystis carinii was the most common pathogen isolated (43 patients). Bronchoalveolar lavage was superior to transbronchial biopsy for the diagnosis of this pathogen, the sensitivities being 90% and 56%. Cytomegalovirus was identified three times by lavage and once by transbronchial biopsy. Neither method detected Kaposi's sarcoma in the one patient shown to have it by open lung bioposy. The complication rate in a concurrent study of bronchoscopy with transbronchial biopsy in 74 consecutive HIV positive patients was 22%. This study does not support the use of transbronchial biopsy in these patients.