The superior properties of poly (ethylene terephthalate) fibers are due to the high degree of orientation and structural order of macromolecular chains. This excellent characteristics are, however, also the source of some negative features such as nearly complete water repellency, difficulty in dyeability, and formation of static çharge ete. One of the ways to improve these undesîrable features is grafting of various monomers upon the poly (ethylene terephthalate) fibers by graft copolymerization. The most common grafting methods namely using ionising irradiatiaon and Chemical initiators w ere briefly mentioned in the first part. The second is ma ini y dwelled upon the changes observcd in the properties of the poly (ethylene terephthalate) fibers as a resu’t of grafth g process.