MERCURY is a metal found in elemental, organic, and inorganic forms in the nature. This substance is present in the composition of earth crust, soil, air, and even in some tissues of plants and sea animals. Each year nearly 3400 tons of MERCURY compounds are released in the environment, which 95% settle in the soil, 3% in the oceans, and 2% in the atmosphere. Different industrial products like medicines, health products (soaps, creams, skin lightening creams), medical instruments (thermometer, sphygmomanometer), some substances in dentistry (amalgam), mirrors, and even some of toys contein MERCURY. All of these compounds may enter into the human body via skin, gastrointestinal and respiratory tracts and cause serious harms. They may cause different signs of TOXICITY, local and general signs and symptoms, and in some cases even they may end up to death. When MERCURY TOXICITY is suspected, in addition to primary evaluations, some special laboratory tests may be of a great help.In order to provide a treatment, the basic steps for all toxicities must be performed to prevent further serious damages,and of course the care giver has to pay attention to specific and non specific features of this TOXICITY.