The prophylactic effect of the oral administration of high-dose amphotericin B syrup for the systemic fungal infection was studied in 36 patients with hematological neoplasms. Twenty nine patients received 2,400 mg/day of Amphotericin B syrup for during the remission induction therapy. One patient received 1,200 mg/day, 3 received 800 mg/day and 3 received 400 mg/day of Amphotericin B syrup. The prophylactic effect was recognized in 24 of 36 patients, 66.7%. As adverse effects gastrointestinal symptoms such as nausea and vomiting, hypochloremia and hypopotassemia associated with hypochloremia was observed in one patient, respectively, however, they were all controllable. The blood levels of Amphotericin B in patients received 2,400 mg/day was 0.092 +/- 0.055 micrograms/ml (n = 40) on 7th day and 0.110 +/- 0.046 micrograms/ml (n = 21) on 28th day, respectively. The administration of high-dose of Amphotericin B syrup is expected not only for the prophylaxis but also for the treatment of the systemic fungal infection.