Pulmonary mucormycosis occur in immunosuppressed patients with a neutropenic treatment or a malignant neoplasia. Although the histological study alone cannot enable species identification, the pathologist usually makes the diagnosis of mucormycosis and can eliminate other filamentous mycoses such as aspergillosis or scedosporiosis. Pulmonary infection caused by Cunninghamella bertholletiae is a very rare lung mucormycosis, particularly in young patients. The histological features of this filamentous mycosis are unusual making the diagnosis of mucormycosis difficult. Mycological study is then crucial for the diagnosis. We report a case of a pulmonary infection caused by Cunninghamella bertholletiae occurring in a young girl with acute lymphoblastic leukemia.