From 1983 to 1991 only isolated cases of aspergillosis in AIDS patients were reported; since 1991, an increasing number of cases have been reported suggesting a recent emergence of this fungal infection. Aspergillosis occurs about 10 to 25 months after AIDS diagnosis in patients with CD4 below 50/mm3. Neutropenia and/or steroid therapy, which are known as predisposing factors in aspergillosis, are noticed in about one half of the patients. Previous pulmonary infection, especially pneumocystosis, are very common. Clinical signs are typical of an invasive pulmonary aspergillosis: constant fever, cough, dyspnea, frequent thoracic pains and haemoptysis. Radiologic signs frequently indicate an interstitial infiltration. Nodular and cavitating lesions, pleural effusions, thoracic lymph node enlargement are often present. Diagnosis procedures are realised on bronchoalveolar lavage by direct examination, culture and antigen detection. Aspergillus fumigatus is the most usually species detected. Post-mortem diagnosis is frequent. Invasive bronchial aspergillosis, localised infections (aspergilloma, otitis, sinusitis) or disseminated infections (nervous system, heart, kidney, lymph nodes, thyroid) are also described. Prognosis is poor even with treatment (amphotericin B or itraconazole). An earlier diagnosis and treatment of the bronchial colonization could probably improve this prognosis.