The results of 115 bronchoscopic examinations and one autopsy in 105 adults with HIV-infection and pulmonary complications are presented. Whereas 51.7% of the events were caused by Pneumocystis carinii pneumonia (PCP), nonspecific interstitial pneumonitis (NIP) without evidence of an infectious or neoplastic condition was the second most frequent diagnosis in 14 patients (12.1%), four of whom exhibited features of lymphocytic interstitial pneumonia (LIP). The clinical, radiological and prognostic aspects of NIP/LIP, which are very similar to those of PCP, and the possible pathogenesis are discussed. The importance of an adequate diagnostic pulmonary workup is emphasized. We suggest classifying patients with NIP/LIP as stage IV E (CDC) and evaluating the efficacy of a treatment with azidothymidine (AZT) in a controlled clinical study.