A 56-year-old man with diabetes and staphylococcal endocarditis received intermittent, brief courses of broad-spectrum antibiotics. Fungal superinfection with Rhodotorula resulted. Rhodotorula was cultured repeatedly from the blood and urine during a period of high fever, while the patient was on adequate antibiotic therapy for staphylococcus. During and after treatment with amphotericin B and massive doses of penicillin, repeated blood cultures were sterile, and the patient recovered from this infection and superinfection. Amphotericin B was given intravenously in gradually increasing amounts until a daily dosage of 1.0 mg. per kilogram was achieved for 3 weeks. One can only speculate whether the fungus actually invaded the heart valves, but therapy was continued for this period because of this possibility. Fourteen months after discharge from the hospital, the patient was well except for a residual right hemiparesis.