The clinical study phase III 071 has showed the new antiemetic Aprepitant in association with a standard therapy (corticosteroid plus a 5-HT3 receptor antagonist) increases significantly the complete response (no vomiting and no rescue treatment) by more than 10 points compared to the standard therapy used in MEC. OBJECTIVES: to evaluate the budget impact implied by the introduction of this new antiemetic on the French sickness funds. METHODS: The MEC were defined according to the recommendations of the Multinational Association of Supportive Care in Cancer (2004). A sample of patients was extracted from the ONCO IMS 2004 database. The inclusion criteria used were: to receive a MEC in association with an antiemetic one containing a corticosteroid and a 5-HT3 receptor antagonist and to have this treatment during the acute and delayed periods. Prices of the antiemetic treatments were taken from the GERS 2004 database. A budget impact model was implemented over a period of four years, based on a stable population and on different penetration and substitution rates of Aprepitant. RESULTS: The results are reported for 10 000 MEC cycles associated to the standard therapy. The penetration and substitution rates of Aprepitant increase over the period from 10% to 25% and from 70% to 95%, respectively. In 2004, the treatment cost is 466 000€. The introduction of Aprepitant increases the cost of the acute phase but decreases it in the delayed one. In the ambulatory care sector the cost decreases over the four years. Every year the net budget impact due to Aprepitant is less than 3%. The fourth year, the treatment cost with Aprepitant is equal to 478 000€. CONCLUSION: The additional costs caused by the introduction of Aprepitant seem fair compared to the gain in terms of complete control of vomiting.