In Europe Rare Disease (RD) is the one which affects less than 1/2000, in the USA 1/1250, while in Japan RD is the one that affects fewer than 1/50,000 patients. EU estimates that 5-8000 distinct rare diseases affect 6-8% of the Population. The impact of rare diseases in the health systems is impresssive: at least 3 million patients in the UK, 4 million in Germany, and between 27 and 36 million EU citizens. There is not a precise register for rare diseases in the Republic of Macedonia. Rare diseases are becoming increasingly important as possible targets of new forms of treatment, as a valuable source of a novel insight in fundamental lows of biology, and in the specific mechanisms of many diseases. Molecular methods have created a better diagnosis and oftentimes treatment. Rare diseases pose significant problem for the patients, since their problems are often not recognized by the medical community and shunned by the health insurance. The cumulative costs of diagnosis and treatment of rare diseases is significant for any society and oftentimes not acceptable for developing countries.