To define the concepts of orphan drugs and diseases, the current situation of clinical investigation of them, the attitude of the pharmaceutical industry and aspects of health legislation, especially in the European Community.We review the history of orphan drugs, the name used for those drugs, apparatus, biological agents and dietetic preparations used to treat diseases so rare as to affect 650 1,000 persons per million inhabitants. Approximately 5,000 of such disease have been identified. Of these, 80% are genetic disorders which are very common in neuropaediatrics, since 50% appear in childhood. Half of these disorders affect the nervous system but in general there are no relative preventive and/or therapeutic methods. In view of the expense involved, the pharmaceutical industry is loath to develop products which are only used in rare diseases. Society cannot tolerate the fact that these patients do not have access to medical progress. For this reason organizations of affected persons (especially the National Organization for Rare Diseases) put pressure on the USA authorities leading to the Orphan Drug Act of 1983 which was subsequently copied by other countries. Since January 2000 there is a similar Regulation in the European Community. Orphan diseases need to be diagnosed early by specialists who have had patients referred to them by general practitioners. However, initial recognition of the disorder is often delayed and late diagnosis occurs in 45% of these rare diseases which make up 10% of human illnesses. Currently over 150 orphan drugs are being used for over seven million patients.The struggle to treat rare diseases must continue, since its true importance is shown when suffered personally.