OBJECTIVES: Orphan drug legislations have been introduced to encourage the development of orphan drugs.  In the European Union (EU), orphan drugs are used for the diagnosis, prevention or treatment of life-threatening or serious conditions that affect ≤ 5 in 10,000 people. It is estimated that approximately 7000 rare diseases exist. We assessed the characteristics and outcomes of the new drug development for rare diseases in the EU. METHODS: Data on therapeutic indications for the cohort of orphan drugs authorised in the EU were extracted from the European Public Assessment Reports of the European Medicines Agency (EMA) and the European Commission Register of medicinal products (up to June 2011). RESULTS: Overall, 64 orphan drugs were authorised in the EU since 2000, corresponding to a total of 77 indications.  Median time from orphan designation to EMA authorisation was 2.6 years (P25-P75: 1.5-4.5 years). Sixty percent of the total indications were for the treatment of rare diseases that affect ≤ 1 in 10,000 people. By therapeutic area, the percentage of indications with a marketing authorisation was heterogenous (e.g., 45% for malignant neoplasms, 32% for blood and endocrine disorders, 6% for cardiovascular diseases, 6% for neurological and mental conditions, or 3% for perinatal conditions, among others). CONCLUSIONS: Regulatory reform efforts have contributed to the development of orphan drugs. Further research is needed to explain whether unmet needs are being addressed among patients with rare diseases .