A total of 2340 patients with underlying malignancy were identified among 22,631 episodes of nosocomial bloodstream infections (BSIs) in a prospectively collected database for 49 hospitals in the United States (Surveillance and Control of Pathogens of Epidemiologic Importance [SCOPE] Project). Data were obtained for the period of March 1995 through February 2001. Gram-positive organisms accounted for 62% of all BSIs in 1995 and for 76% in 2000 (P<.001), and gram-negative organisms accounted for 22% and 14% of all BSIs for these years, respectively. Neutropenia was observed in 30% of patients, so neutropenic and nonneutropenic patients were compared. In both, the predominant pathogens were coagulase-negative staphylococci (32% of isolates recovered from neutropenic patients and 30% of isolates recovered from nonneutropenic patients). The source of BSI was not determined for 57% of patients. The crude mortality rate was 36% for neutropenic patients and 31% for nonneutropenic patients.