The combination of beta-lactam antibiotics and new quinolones is a form of broad spectrum antibiotic therapy rapidly bactericidal in vitro which could be an alternative to the classical combination of beta-lactam antibiotics and aminoglycosides in the first line treatment of febrile episodes in patients with neutropenia. The treatment of 37 initial febrile episodes (12 cases of septicemia, 7 infectious sites and 38 cases of fever of unknown origin) in 33 neutropenic patients (PMN leucocytes less than 500/mm3) using the combination of a third generation cephalosporin (cefotaxime or ceftazidime) and a new quinolone (pefloxacin) resulted in an 86% immediate success rate (32 cases/37). Results and course during treatment were similar in both groups (cefotaxime or ceftazidime). A second febrile episode occurred in 11 cases (4 superinfections, 2 chest infections, 5 fevers of unknown origin). Clinical acceptability was satisfactory in both groups. Minimal and transient changes in liver function tests were observed in 19% of the successfully treated patients. Study of quantitative aerobic stool cultures revealed the emergence of resistant bacterial strains, essentially Pseudomonas sp. (6 cases). More extensive trials should provide a better view of the role of this new combination in the first line treatment of febrile episodes in the neutropenic patient.