Candida parapsilosis is rarely isolated from blood cultures. Our hospital surveillance detected an increased rate of isolation of C parapsilosis during a four month period. Fourteen postoperative patients receiving intravenous (IV) hyperalimentation and eight burn patients receiving IV albumin were involved. Hectic fever, the major clinical manifestation, was seen in 61% of cases. Therapy in the postoperative patients consisted merely of discontinuing IV catheters and hyperalimentation, while amphotericin B was needed in five of eight burn patients to control persistent fungemia. Epidemiologic analysis identified a source of the organism in the IV-additive preparation room where C parapsilosis was found contaminating a vacuum system. Organisms apparently refluxed into IV bottles when aliquots were removed to accommodate additives. Of 103 patients who received fluids prepared with the contaminated system, 21% became infected with C parapsilosis. Infection surveillance was instrumental in detection and control of the outbreak. Routine guideline should be established to insure the sterility of IV fluids containing additives.