The purpose of this study was to achieve a cost-effectiveness analysis of the alternative piperacillin-tazobactam (PTZ) versus ceftazidime (CFZ) both used in conjunction with amikacin, as a therapy in post-chemotherapy febrile neutropenia. METHOD: Efficacy data were obtained from the two clinical trials performed by the European Organization for Research and Treatment of Cancer (EORTC) and the Gruoupe d´etude des Aplasies Febriles (GAF). A cost-effectiveness analysis has been carried out using the software "Multiprograma DUE-Estudios farmacoeconómicos". It has been considered: the alternatives (PTZ and CFZ), the type of pharmacoeconomical study (cost-effectiveness analysis), the pathology (febrile neutropenia), the perspective of the study (hospital), the number of patients (493 and 498, respectively) and the type of case (dependent). The following costs have been imputted to each one of the branches of the tree decision according to the software: the acquisition cost, the preparation and administration cost, the monitoring cost, the treatment of adverse effects, the structural cost and the cost of therapeutic failure. RESULTS: The cost per unit of effectiveness was $ 5,250 with PTZ and $ 5,850 with CFZ. The incremental cost was $ 1,472 per additional case prevented with PTZ instead of CFZ. The sensitivity analysis carried out regarding the variables: the percentage of success, the percentage of overinfections and the price of the parmaceutical product, veritied the first results of the cost-effectiveness analysis. CONCLUSIONS: The alternative PTZ presented a better cost-effectiveness relation to the CFZ in the treatment of the fever and bacteriemia in neutropenic patients, offering a reduction of the cost per unit of treatment successful of $ 635.