When undrawn amorphous poly(ethylene terephthalate) (PET) fibers are drawn in ethanol, multiple necking generates, and ethanol is sucked into the fibers. This phenomenon is called infusion. It should be noted that the diffusion of ethanol into PET fibers never proceeds by simply dipping the undrawn or drawn PET fibers into ethanol. Infusion of ethanol into PET causes solvent-induced crystallization. Accordingly, highly oriented and highly crystallized fibers can be produced without heating. If dyestuff is dissolved in ethanol, dyestuff also infuses into the fiber, and coloring of PET fiber can be achieved without the application of high temperature and high pressure. Fundamental analysis of this process was carried out through the batch-type drawing process by changing the drawing speed, draw ratio, ethanol concentration, etc. To explore the industrial applicability of this unique behavior, continuous drawing of PET fiber in ethanol was also carried out, and drawing behavior as well as the structure and properties of the resultant fibers were analyzed in detail.