When patients with cancer receive chemotherapy (drugs used to kill cancer cells), normal cells in the bone marrow are often temporarily damaged or destroyed. Since the bone marrow produces cells that fight infection (white blood cells, or leukocytes), chemotherapy often increases susceptibility to infection. These infections are usually due to bacteria or fungi. It is often difficult to determine which organism has caused infection. Fungi are difficult to treat and often cause fatal complications, unless treatment is started early or before infection starts. Patients with low white blood cell counts due to chemotherapy and suspected fungal infection usually receive amphotericin B. Although 43% to 72% of these patients improve while taking this drug, bad side effects occur in 35% to 82%. An effective, less toxic, alternative treatment would be helpful.