Cytomegalovirus is capable of causing disease in immunocompromised patients. In people infected by the Human Immunodeficiency Virus (HIV) it becomes an important agent when there is advanced immunosupression. Its role as a pulmonary pathogen in these patients has been questioned. In the case of pneumocystosis the presence of Cytomegalovirus doesn't seem to worsen prognosis, except in cases where corticosteroids are used. Authors present two cases of patients with HIV infection and advanced immunosupression who were admitted in the intensive care unit for respiratory failure. In both Pneumocystis jirovecii was isolated from.