Cells from many organisms increase production of proteins when their environment changes. Because this group of proteins was first found in cells that were exposed to high temperatures, they are called “heat shock proteins” or HSP. Heat shock proteins are also being synthesized under different kind of stress conditions, like inflammation, infection, ischemia and exposure of the cell to toxins or malignant transformation. Heat shock proteins act as molecular chaperones for protein molecules. Usually they are cytoplasmic proteins and they function in various intra-cellular processes. They play an important role in proteinprotein interactions, including folding and assisting in establishing of proper protein conformation, and prevention of inappropriate protein aggregation. Heat shock proteins have been named according to their molecular weights.