Lung infections caused by invasive filamentous fungi are very rare conditions in AIDS, but must be considered in patients with profound immune suppression especially in the presence of additional risk factors, such as hematologic malignancies, corticosteroid therapy, neutropenia, and chemotherapy. The authors report a case of dual lung infection caused by Aspergillus and Mucor, which occurred in a 34-year-old AIDS patient who was treated with chemotherapy for oral plasmablastic lymphoma. The case presented clinically with low grade fever and pulmonary cavitation, which suggested tuberculosis. After extensive investigation the diagnosis of mucormycosis was established and the patient was treated sequentially with liposomal amphotericin B and posaconazole. Despite a reduction in the size of the pulmonary cavitation, improvement of the lung interstitial infiltrates and clinical recovery, the patient was submitted to cardiothoracic surgery given the aggressive behavior of this invasive fungus. Histology of the surgical specimen showed numerous hyphae with a morphologic pattern compatible with Aspergillus as well as hyphae that were suggestive of Mucor.