During the five-year period 1984-1988 we received 192 specimens from 180 patients infected with the human immunodeficiency virus (HIV) for investigation of Legionella infection. The majority of specimens were bronchoalveolar lavage (BAL) fluids (84%), but tracheal suctions and lung tissue from autopsies were also examined. The diagnostic methods used were a direct immunofluorescence assay (DFA) for the detection of Legionella antigen, and culture on buffered charcoal yeast extract (BCYE-alpha) media. All specimens were also examined for the presence of other bacterial lung pathogens, and all BAL specimens additionally for Pneumocystis carinii and mycobacteria. Legionellosis was not found to be common among HIV-infected patients, as only six specimens (3%) from six patients were found positive by DFA, and no specimens were culture-positive for Legionella species. Dual infection with Legionella and P. carinii occurred in two patients. Clinical data of the six patients are presented, and currently used methods for diagnosing legionellosis are discussed.