OBJECTIVES: To evaluate the budget impact of increased micafungin use to treat invasive candidiasis in the ICU setting in Spain. METHODS: A decision tree model was developed to simulate the management of invasive candidiasis over 19 days. Patients enter the model and initiate treatment with micafungin or caspofungin. On Day 4, if treatment is effective, patients continue with their existing treatment or switch to fluconazole on Day 7 (if they have susceptible isolates), and transfer to a general hospital ward. If treatment is not effective, patients switch to L-amphotericin B or an alternative echinocandin and remain in ICU. Those who fail second-line therapy are assumed to be at higher risk of death. Model inputs included: national disease epidemiology; mycological success (eradication of Candida) and overall success (Candida eradication and resolution of all signs and symptoms of infection); mortality rates; and national medication and hospitalisation costs. A network meta-analysis was conducted to estimate the relative benefit of micafungin and caspofungin. Outcome measures included the overall treatment cost (medication and hospital care costs) and the budget impact over 5 years, based on treatment of 3,764 patients. RESULTS: The average cost per patient was €17,483 for micafungin (€4563 for medication; €12,921 for hospital costs) and €19,721 for caspofungin (€5364 and €13,906, respectively). The lower costs for micafungin reflect a higher probability of mycological success (82 vs. 57%) and overall success (74% vs. 60%). The cumulative budget impact of increasing micafungin use from 2.0% to 2.5% over 5 years (whilst decreasing caspofungin use from 2.2% to 1.7%) was –€99,806 (clinical success used to determine treatment switching) or –€172,607 (switching based on mycological success). CONCLUSIONS: Use of micafungin is associated with lower overall costs per patient than use of caspofungin. Increasing micafungin use translates to significant savings over 5 years in the Spanish healthcare setting.