A lysis-centrifugation system (Isolator; E. I. du Pont de Nemours & Co., Inc., Wilmington, Del.) was compared with a biphasic brain heart infusion (BHI) medium in a prospective study of 5,125 fungal blood cultures. The Isolator recovered 90.3% of the positive cultures, compared with 63.4% recovered by the biphasic BHI medium. Overall, the detection of fungemia was increased 36.6% by the Isolator. Mean recovery times for yeasts were 2.12 and 4.90 days for the Isolator and BHI bottles, respectively. Cultures of Histoplasma capsulatum required 8.0 and 24.14 days for recovery by the Isolator and BHI bottles, respectively. The Isolator provided a more rapid and sensitive means of detecting organisms associated with fungemia.