This work focused on corrosion of carbon steel bolted GECM/AI parts in tap water and NaCl solutions. In tap water and NaCl solutions open circuit potential of GECM and its potentials in series of carbon steel bolt＞Ti＞Al became active. Regardless of test materials open circuit potentials in tap water were noble and increasing NaCl concentration its potentials became active. Immersion test of single specimen showed that no corrosion occur in Ti and GECM. In tap water carbon steel bolt didn`t show red corrosion product and in chloride solutions corrosion rate in 1% NaCL solution was greater than its rate in 3.5% NaCl solution and red corrosion product in 1% NaCl solution was earlier observed than that in 3.5% NaCl solution. It seems that this behavior would be related to zinc-coatings on the surface of carbon stee l bolt. On the other hand aluminium was corroded in tap water and chloride solutios. Corrosion of aluminium in tap water was due to the presence of chloride ion in tap water by sterilizing process.