The methodological approach of the economic evaluation of drugs in pediatrics is illustrated by the case study of the prophylaxis for RSV infections using palivizumab in the French setting. The indications for the reimbursement of this treatment have been restricted to premature children with bronchopulmonary dysplasia (BPD) or hemodynamically significant congenital-heart disease. A model was developed primarily using the results of the pivotal clinical studies on palivizumab. Unit costs were estimated (2006 values) in both societal and payer's perspectives. An assumption was made and discussed on the benefits of the prophylaxis on mortality. Based on the different data available and the estimated costs and benefits, different cost-effectiveness ratios (CERs) were estimated from both the society's and payer's points of view. A discount rate of 3% was applied to benefit. The CER obtained in the most unfavorable case is considered acceptable for the innovative-medical technologies in the French-healthcare system. Some of the parameters used by the model will be illustrated from the EPIPAGE study data from 2 of the 9 regions involved in this study: this evaluation suggests that the children not having an RSV infection during their 1st year of life will continue to require significantly fewer hospitalizations in the following years. These additional evaluations also suggest that the model overestimates the costs of the treatment with regard to the true medical situation. This could be explained by the model not using the children's exact weight or the real number of injections because the children had been discharged from the maternity ward based on their date of birth and the epidemic period. In spite of these factors, RSV prophylaxis using palivizumab in premature children with BPD or hemodynamically significant congenital-heart disease can be considered cost-effective in France.