Abstract: All organism respond to elevated temperatures and many other stresses with the production of a defined set of proteins called heat shock proteins ( HSPs). The basic characteristics of HSPs are highly conserved, diversed and the heat shock response is temporal. Although HSPs were first characterized because their expression increased in response to elevated temperature, some HSPs are found at sighificant levels in other stresses, in normal, nonstressed cells and produced at particular stages of cell cycle or during development in the absence of stresses. The findings indicated that HSPs have many functions, including molecular chaperones, thermotolerance, chilling tolerance, a special role in the development of organisms and other biochemical functions in cell metabolism, The association of HSF with HSP70 may be important in the regulation of heat shock gene transcriptional activity. The expression of heat shock gene is self-regulated by HSP.