Besides well-known diseases, about 5,000 identified are classed as "orphan" because of the lack of any response in terms of diagnosis, prevention and treatment. The development of drugs for these diseases, intended for a limited number of patients, often requires considerable research, and subsequently, cost. The aim of the present article is to discuss the ethical, political and economic problems relevant to the development and disposal of drugs specifically designed for these diseases, now commonly called "orphan" drugs. These questions have been raised at discussions and dialogues at the European Parliament where European regulations on orphan drugs were adopted on December 15, 1999. These regulations (141/2000/EEC) came into effect in the European Union on January 22, 2000, and are widely inspired from the American model. The regulations stipulate that the criterion for designation of the drug is based on a disease prevalence of 5/10000). Advantages commonly recognized for the orphan drug status concern: community registration (centralized marketing approval), eligibility for grants and national or community fiscal support, lower or canceled registration fees, technical contribution via the European drug agency (EMEA), and exclusive rights for a 10-year period. On May 12, 2000, the European Commission completed the status by adopting rules establishing the criteria used for designating a drug as an orphan drug. This document implements the dispositions available to pharmaceutical firms inciting them to invest in the development of orphan drugs.