Ong-keun jook(Korean whole rice porridge)is a traditional Korean porridge made with whole rice. The aim of the present study was to evaluate the effects of gamma-irradiation on the microbial and physicochemical characteristics of rice porridge gamma-irradiation, even at a 1-kGy dose, decreased the total bacteria in cooked rice porridge to lower than the detectable limit($10^2CFU/g$). The viscosity of gamma-irradiated rice porridge was decreased compared to that of control. Upon examination of granule morphology by SEM, cracks were observed on the starch granules in samples irradiated at above 5 kGy. The results of the DSC curve suggest that gamma-irradiation delayed retrogradation of cooked rice porridge. Based on the present results, gamma-irradiation was helpful for developing sterile and tube diets that are needed for ill, old or infant subjects.