Pulmonarycosis is a rare disease, which refers to an infection by fungi belonging to the order Mucorales. This organism usually invades the skin, nose mouth, paranasal sinus, gastrointestinal tract, lung, brain, eyes and so forth. It usually occurs in patients with diabetes mellitus, hematological malignancy or other immunocompromised states. Until recently, this disease was rarely diagnosed before death. We report a case of pulmonary mucormycosis in a woman with poorly controlled diabetes mellitus. This is the first case in Taiwan of pulmonary mucormycosis diagnosed preoperatively and treated successfully by lobectomy only. Persistent pulmonary lesions resistant to antibiotic treatment in high risk patients should arouse the suspicion of mucormycosis. Prompt bronchoscopic examination, open lung biopsy and transthoracic pulmonary aspiration cytology and biopsy should be done. Surgical resection of localized lesions remains the treatment of choice.