AIDS (acquired immunodeficiency syndrome) seems to be related to human immunodeficiency virus (HIV) and is characterized by severe T-helpers lymphocyte dysfunction. Many of the AIDS patients (47-70%) develop pulmonary manifestations, both infectious and neoplastic, in the course of their disease. In the Department of Infectious Diseases of our Hospital are studied many patients HIV+. Every year 246 seropositive new patients have been discovered. Among them we have studied 25 subjects with respiratory disease, by chest radiographs; successively, according to clinical picture, we have performed thoracic computed tomography, Gallium scintigraphy, fiberoptic bronchoscopy with transbronchial biopsy (TBB), bronchoalveolar lavage (BAL); the majority of these patients (68%) had AIDS, only 28% had ARC and 4% had PGL. In our experience, the diagnosed diseases were mainly infections (92%), and most frequently (52%) due to Pneumocystis carinii, alone or in association with other etiologic agents. We have not found pathognomonic radiographic abnormalities, but chest X-ray evaluated with clinical and laboratory data, may often be useful to obtain diagnostic indications and in order to determine a more specific and aggressive diagnostic approach.