In this prospective pilot study we evaluated the efficacy of blood cultures (BC) in detecting bacteremia and fungemia prior to the occurrence of infectious signs. Between February 2003 and July 2003, BC were performed twice weekly in neutropenic hematological patients using blood drawn from central venous catheters. Microbial growth prior to the onset of infectious symptoms was detected in 3 of 45 neutropenic episodes in 39 patients and led to modifications in patient management. These results suggest that further prospective studies are warranted to determine the clinical usefulness of surveillance with BC in neutropenic patients.