Invasive fungal infections are an important cause of morbidity and mortality in immunosuppressed bone marrow and solid organ transplant recipients. Treatment with amphotericin B, the drug of choice for these infections, is however often limited by toxicity. Ten transplant patients receiving a liposomal amphotericin B formulation (AmBisome) were compared to ten retrospective control patients given conventional amphotericin B. Each group included bone marrow (8), kidney (1), and liver transplant (1) recipients. Conventional amphotericin B treatment was instituted due to nine Candida infections, and one Aspergillus fumigatus infection. In the AmBisome group treatment was instituted due to eight Candida infections, one infection caused by Saccharomyces cerevisiae and in one case as prophylactic treatment. In the amphotericin B group, maximal daily doses ranged from 0.1 to 0.65 mg kg-1 and cumulative doses were 21-836 mg kg-1 and were given over 3-32 days. In the AmBisome group, maximal daily doses ranged from 0.9 to 2.3 mg kg-1 and cumulative doses ranged from 225 to 3525 mg kg-1 over 8-28 days. All patients in the amphotericin B group experienced severe toxicity, especially nephrotoxicity which in four cases caused withdrawal of the drug. In contrast, the only adverse reaction in the AmBisome group was cholestasis in one patient. Only three out of ten patients in the amphotericin B group responded to treatment, seven patients died and six patients still had evidence of invasive fungal infection at autopsy. In contrast, eight out of nine patients in the AmBisome group responded to treatment, and the patient that received prophylaxis had a successful course.