Two patients with acute leukemia in whom disseminated Trichosporon beigelii infection developed are reported. The T. beigelii infection developed in the first patient while he was receiving 5-fluorocytosine. He was treated with amphotericin B in addition to 5-fluorocytosine. Despite the continued antifungal therapy, multiple organs were invaded by the organisms at autopsy. The second patient was treated with miconazole and norfloxacin. Although this combination antifungal therapy seemed to be effective, this patient required splenectomy for cure of the infection.