This is a retrospective study comparing the methods of preventing fungal infection in a total of 420 episodes of chemotherapy-induced neutropenia of more than 10 days' duration between 1986 and 1992 in 104 patients with acute leukemia and 62 patients who underwent bone marrow transplantation. The episodes were divided into five groups according to the prophylactic regimens (group 1, oral amphotericin B (OA) only; 2, OA and nebulization of amphotericin B (NA); 3, OA and NA with a laminar air flow system (LAF); 4, oral fluconazole (OF) and NA; 5, OF, NA, and LAF. The total numbers of neutropenic episodes were 115, 141, 95, 37, and 32, respectively. A total of 15 episode of invasive fungal infections were documented. Aspergillosis was seen on two occasions each in groups 1 and 2, while none was seen in the patients who were under the LAF system. Nebulization of amphotericin B did not have a significant preventive effect in this study and it needs to be evaluated further by a randomized study.