Polyester fiber was pretreated with chlorinated hydrocarbon/water emulsions of various compositions. The chlorinated hydrocarbons used in this experiments were perchloroethylene, trichloroethylene and perchloroethane. The dyeing behaviors of the pretreated fibers with C.I. Disperse Violet I in water and that of untreated fibers with C.I. Disperse Violet I in emulsion were studied with reference to changes in the clatter properties of fiber. Also density and x-ray diffraction of the fibers were investigated as measure of crystalline region. The results obtained are briefly discussed in teams of the plasticization of the fiber structure formed during the pretreatment and chlorinated hydrocarbon/water emulsions dyeing. The results are as follows: 1) Shrinkage of polyester treated with chlorinated hydrocarbon/water emulsions was greater than that of sample treated with solvents alone. 2) The crystalline growth of polyester treated with the emulsion was also greater than that treated with solvents alone, and this tendency was in contrary order with regard to the crystal orientation. The order of increasing crystalline growth and decreasing crystalline orientation was, perchloroethylene/water<perchloroethane/water 3) Equilibrium dye absorption and initial rate of dyeing, of polyester treated with emulsion were greater than those of samples treated with solvents alone. 4) The equilibrium dye absorption and the initial rate of dyeing in emulsion dyeing were higher than that of pretreated samples with emulsion in water dyeing.