A 29-year-old woman with acute myelogenous leukemia in relapse at the end of a nine-month period of remission was admitted to hospital where intensive antileukemic therapy was started. Antibiotics were given when she developed a fever and, when oral thrush appeared, intravenous amphotericin B was initiated. After 16 days, the amphotericin B (at a total dose of 295 mg) was discontinued because of side effects and 12 days later, when a lung biopsy had revealed mucormycotic hyphae in infarcted tissue in the left upper lobe, fluconazole (300 mg daily by intravenous infusion over a period of two hours) was substituted. This was continued for one month with clinical and radiologic improvement in the lung condition and no attributable adverse effect. At this juncture the patient died of intractable heart failure. We suggest that fluconazole may be an acceptable alternative to amphotericin B in the treatment of pulmonary mucormycosis.