Fungal endocarditis occurs in heroin addicts, patients who have undergone cardiovascular surgery, and patients who are treated for prolonged periods with intravenous fluids and broad spectrum antibiotics. The organisms associated with endocardial infection differ in each of these groups. Candida parapsilosis is the fungal species most commonly isolated from narcotics addicts, Aspergillus species are most frequently found in patients after cardiovascular surgery, and Candida albicans occurs most frequently in patients who have received prolonged courses of intravenous fluids and antibiotics. Despite the availability of antifungal antibiotics and surgery, over 80% of patients with documented fungal endocarditis die of this infection. Thus, early diagnosis of fungal invasion and prevention of established endocardial infection are essential. Antifungal therapy and/or careful followup should be considered in patients in whom "transient fungemia" is documented by blood culture and serological and untrasonic techniques should be further evaluated as a means of early diagnosis.