The objective of the presented, randomized study was to compare the efficacy of antimicrobial monotherapy with imipenem (3x0.5g/d) to a combination therapy with cefotaxime (3x2g/d) plus piperacillin (3x4g/d) for empirical treatment of infections in neutropenic patients. In 165 patients, 237 infectious episodes were evaluable. The overall response rate of patients treated with cefotaxime plus piperacillin was 67/115 (58%), of those treated with imipenem 66/122 (54%), In patients not responding to the initial therapy regimen within 2 or 3 days, the antimicrobial therapy was modified, After therapy modification 85/100 patients were cured, Fever of unknown origin (FUO) showed the most favourable course compared to other infection types, with a response in 46/59 (78%) and in 35/50 (70%) cases, respectively, In comparison, pneumonias were successfully treated in only 3/21 (14%) and 7/37 (19%) cases. Even including patients with modified therapy, only 66% (21/32) of pneumonia episodes responded, The unfavourable results in pneumonias is mainly due to the high rate of 13 systemic mycoses in this group (22%). Overall, a similar response was observed in patients treated with cefotaxime plus piperacillin in comparison with imipenem, In primary bacteremias however, an advantage was observed in patients treated with imipenem (20/27; 74%) compared with cefotaxime plus piperacillin (11/23; 48%).