Ninety-one immunosuppressed, high-risk patients suspected of having invasive candidiasis were tested during their septic episode for the presence of candida precipitin (CP) antibody using the counterimmunoelectrophoresis (CIE) method. In 12 patients, systemic candidiasis was confirmed but only 6 of these (50%) had candida precipitins. In 14 "questionable" cases who died without a definitive diagnosis, 8 (57%) had precipitin antibody. Of the 65 patients who did not have serious candida infection, 20 (31%) had candida precipitins. In this population we found the presence of candida precipitins to be neither sensitive (50%) nor specific (69%) for the diagnosis of invasive candidiasis.