Chlorinated polyester fabric with upto 20% chlorine content was prepared by irradiating the fabric in chlorine gas at about atmospheric pressure with γ-rays at room temperature.When the chlorinated fabrics were subjected to an alkali-treatment such as heating up to 100°C in aqueous solution of sodium carbonate, it caused, more or less, a weight loss and a decrease in mechanical strength of the fabrics. The extent of damage of the fabrics was dependent on the condition of alkali-treating. The chlorinated fabrics after any alkali-treatment, however, exhibited improved dye-uptake. Hygroscopicity of the treated fabric was examined by measuring wicking time, which decreased considerably by the alkali-treatment after the chlorination, indicating increased hygroscopicity.Scanning electron microscopic observation of the fabric before and after the alkali-treatment revealed that a large number of pores (the size up to 10μ) were formed by the treatment on the surface of the fabric. Enhancement of the dye-uptake and improvement of hygroscopicity may be at least partially attributed to the formation of these pores by the alkali-treatment.