An 11 year old boy with medullary aplasia developed extensive mycosis of the face. This mucormycosis is a rare affection that appears in patients with predisposing disease (diabetes, blood disorders) and is easily diagnosed, if considered, from clinical features. Diagnosis is confirmed by histopathology, culture sometimes identifying the causative fungus. Despite the intrinsic serious course of this affection (facial necrosis, death) prognosis appears to be related essentially to the rapid control of the subjacent disease.