OBJECTIVES: Alkaptonuria (AKU) is a rare disease with no effective treatments, characterised by excess homogentisic acid in the circulation. This leads to progressive inflammation of cartilage tissue, joint pain and need for joint replacement. Nitisinone is an orally-administered drug that reduces homogentisic acid levels, which is under investigation as a potential treatment. This study assessed the cost-effectiveness of nitisinone in the UK healthcare setting.