Use of cyclosporin A has improved survival in patients submitted to cardiac transplantation. However, high cost of cyclosporin poses a problem for many patients in Chile. Ketoconazole is able to reduce hepatic metabolism of cyclosporin and thus prolong therapeutic levels. A 74 to 82% reduction in cyclosporin requirements was obtained in a cardiac transplant patient by adding ketoconazole. No renal damage was detected. Therefore, this drug association may help extend cardiac transplantation programs in Chile.