Two hundred thirty-five fungal infections occurred in patients with malignant diseases over a four-year period. One hundred eighty-eight were due to Candida species and Torulopsis glabrata and are reviewed herein. The frequency was highest in patients with acute leukemia (11.9 per 100 registrations) with a frequency of 0.8 per 100 registrations in all cancer patients at this institution. Three or more predisposing factors were present in more than 50 percent of the cases; antecedent myelosuppression, chemotherapy, and antibiotic therapy were most common. Blood cultures were positive in only 35 percent of patients with disseminated candidiasis. Twenty-nine of 55 patients (53 percent) had candidemia without identifiable organ infection recovered. Eleven were given no systemic antifungal therapy and recurrence of infection was documented in two patients. Only six (4.5 percent) of 133 patients with proved deep organ infections recovered. Respiratory failure was the clinical cause of death in 62 percent of patients. Clinical features, cultures, and serologic tests were usually of no assistance in establishing the diagnosis early in the course of the infection.