Bronchoscopic diagnosis was performed in 91 patients with 100 episodes of fresh pneumonia. In already existing immunosuppression (n = 51, Group A) pathogens were most frequently identified via bronchoalveolar lavage (70%); in patients without immunosuppression (n = 49, Group B) the identification quota in respect of the central bronchial secretion (53%) and bronchoalveolar lavage (47%) were comparable. In Group A the most frequently occurring pathogens were Pneumocysti carinii (n = 18) and Aspergillus fumigatus (n = 7), in Group B Streptococcus pneumoniae (n = 8) and Staphylococcus aureus (n = 7).