High molecular weight poly(ethylene terephthalate) (PET) was prepared by using a modified postpolycondensation method. Gelation temperature(아 and gel melting temperature (Tt) of PET-nitrobenzene gel were measured, and gel forming process and non-isothermal c.ystallization behavior were investigated. and 75, was increased with increasing concentration of PET and decreased with increasing molecular weight of the polymer. The crystallization rate was decreased with increasing molecular weight and concentration. The high molecular weight PET in phenol/tetrachloroethane (614%) was cast onto film. Optimum critical concentration in the solvent casting was determined by viscosity measurement, and it was found that this concentration was decreased with increasing molecular weight of the polymer. The solvent cast film exhibited almost same modulus, but its tensile strength was increased with increasing molecular weight of the polymer.