New evidence shows that antibiotic prophylaxis in neutropenic patients reduces mortality, febrile episodes, and bacterial infections. For patients with acute leukemia or those who undergo bone marrow transplantation, prophylaxis with fluoroquinolones diminished the risk of death from any cause by 33% (95% confidence interval [95% CI], 2-54%). Thus, 55 patients who have acute leukemia or who undergo bone marrow transplantation must receive prophylaxis to prevent 1 death. In 4 studies that included patients with solid tumors or lymphoma, prophylaxis reduced the rate of death during the first month (relative risk, 0.51; 95% CI, 0.27-0.97), and 82 patients had to receive prophylaxis to prevent 1 death. The main argument brought against prophylaxis is the induction of resistance. Patients who received prophylaxis did not experience more infections caused by resistant strains than patients in the control group. The recent GIMEMA study was con- N ew evidence shows that antibiotic prophylaxis in neutropenic patients reduces mortality, febrile episodes, and bacterial infections. A systematic review and meta-analysis of randomized controlled trials 1 demonstrated that death from all causes was reduced by 34% (95% confidence interval [95% CI], 21-45%) in neutropenic patients who received any antibiotic prophylaxis and by 40% (95% CI, 17-56%) in patients who received quinolones for prophylaxis. in addition, the occurrence of febrile episodes and bacterial infections decreased significantly (Table 1). Most of the studies that were included in that meta-analysis addressed patients with hematologic malignancies. In the most recent and largest randomized controlled trial that included patients in whom neutropenia was expected to occur for more than 7 days (mainly with acute leukemia and autologous peripheral blood stem cell transplantation), 2 patients who received levofloxacin as prophylaxis had a relative risk (RR) of 0.54 (95% CI, 0.25-1.16) for mortality compared with the placebo group: a Dr. Cullen has received honoraria from Sanofi Aventis.We thank Dr. Vivianne Tjan-Heijnen and Ms. Muriel Debois for supplying us with full data regarding mortality from their study.