We analyzed the efficacy of imipenem/cilastatin alone (group I, 197 patients) or in combination with a glycopeptide (group I + G, 231 patients) as first-line antibiotic therapy for 2 consecutive cohorts of autologous stem cell transplantation (ASCT) recipients with febrile neutropenia. From June 2001 to June 2002, patients received imipenem/cilastatin (500 mg/6 hours), and from July 2002 to December 2003, they received imipenem/cilastatin as for group I plus a glycopeptide (vancomycin, 1 g/12 hours or teicoplanin, 400 mg/day). Fever of unknown origin accounted for 33.5% of episodes (66 patients) in group I and 50% of episodes (116 patients) in group I + G (P = .005). Bacteremia occurred in 55 patients (28%) in group I and in 51 patients (22%) in group I + G (P = .16). Resolution of fever without modification of the therapy regimen was observed in 108 patients (55%) and 159 patients (69%) in groups I and I + G, respectively (P = .003). The median interval to defervescence (4 days) and overall mortality were similar between groups. Inclusion of a glycopeptide in the initial antibiotic regimen for febrile neutropenia results in a higher success rate without modifying the regimen. However, glycopeptide inclusion does not improve the interval to defervescence or mortality rate.