A PCR assay was developed for the diagnosis of candidemia. Primers were selected to amplify a 158-bp segment from the Candida actin gene that was detected by hybridization with a 32P-labeled oligomer probe. The lower limit of detection was DNA extracted from 10 Candida yeasts/sample, or 25 fg of purified Candida albicans DNA. This PCR was specific for medically important Candida species. Circulating Candida DNA was detected by this PCR from plasma of mice with induced candidemia and from sera in 11 (79%) of 14 patients with blood cultures positive for Candida species. This PCR may offer a sensitive method for diagnosis of candidemia.