We assessed the efficacy of a piperacillin (3 x 4 g/d) and netilmicin (5 mg/kg/d) combination therapy for infections in febrile neutropenic patients. The study was conducted over a 30-month period and 203 patients were included. Bone marrow transplant recipients were not included in this study. Origin of infection was documented in 101 (50%) episodes: 33 fungal, viral or parasitic infections and 68 bacterial infections mainly composed of septicemia. Of the 169 evaluable patients with proved bacterial infections or non-documented infections, 129 (76%) recovered with the piperacillin and netilmicin combination treatment. All gram-positive bacterial infections failing first line therapy were cured after the addition of vancomycin. Piperacillin and netilmicin appeared very effective in this large monocentric prospective study. It does not seem necessary to include vancomycin in first line therapy of infections of the neutropenic patients in our institution; however, vancomycin must be added early in the case of suspected or documented staphylococcal infection failing empiric treatment.