Disseminated mucormycosis is a rare fungal infectious disease with a high mortality rate and is infrequently diagnosed ante mortem. It is most frequently seen in immunocompromised hosts such as diabetes mellitus, hematologic malignancies, or in the long-term use of steroids or chemotherapeutic agents. Tissue invasion by the hyphae of mucormycosis must be seen microscopically to establish the diagnosis. Treatment consists of correction of the predisposing condition, surgical debridement, and amphotericin-B therapy. A 35-year-old man was admitted through the emergency room due to fever and the right flank pain. He had received an allogenic bone marrow transplantation eight months ago and had been medicated with prednisolone and cyclosporine since the procedure. He was diagnosed with disseminated mucormycosis that involved the spleen, right kidney, and right lung. He is being successfully treated with amphotericin B, flucytosine, and liposomal amphotericin B.