Amphotericin B, a polyene antibiotic effective against eukaryotic cells, can eliminate the trypomastigote form of Trypanosoma cruzi from blood stored at 4°C. This antitrypanosomal effect can be achieved with a concentration of 3 µg/ml within 48 hours. This concentration of amphotericin B does not produce hemolysis over a period of 3 weeks. Amphotericin B methyl ester and nystatin are not effective. Amphotericin B may be considered as a replacement for crystal violet in blood bank blood to prevent transfusion-induced Chagas' disease.