OBJECTIVES: Prolonged-release (PR) fampridine is a first-in-class treatment for the management of walking disability in multiple sclerosis (MS). The purpose of this study was to evaluate the budget impact of PR-fampridine introduction in the treatment of MS patients with an Expanded Disability Severity Scale (EDSS) score between 4.0 and 7.0 in Taiwan. METHODS: A budget impact model was developed with a monthly cycle Markov-chain to evaluate the cost implications of PR-fampridine use to the Taiwan healthcare payer.  All costs in the model were sourced from the Taiwan National Health Insurance formulary and are presented in Taiwan dollars (NT$). Response rates of 35% and 43%, derived from pivotal Phase III trials of PR-fampridine, were applied. The budget impact was calculated for a 5-year time horizon. The base case analysis included the treatment costs of PR-fampridine only. Sensitivity analyses were conducted on the impact of PR-fampridine on direct costs and on market share. RESULTS: For the year 2012, the model estimated 79 patients with EDSS between 4.0 and 7.0 and walking impairment eligible for PR-fampridine treatment.  Budget impact after the introduction of PR-fampridine using a patient response rate of 35% was NT$241,000 rising to NT$3,225,000 over the 5-year time horizon. Applying a 43% response rate resulted in a budget impact of NT$285,000 in 2012 which equates to a 3.61% increase in spending. CONCLUSIONS: Walking difficulty is one of the most commonly reported disabilities in MS patients and PR-fampridine is the only medication indicated for symptom alleviation. The introduction of PR-fampridine leads to a manageable budget impact in Taiwan as well as reduces the debilitating burden of walking disability in MS patients. Future studies are required to investigate the direct cost offsets as a result of treatment with PR-fampridine.