This study was conducted to clarify the varietal differences in the occurence of coarse grain texture due to the high-temperature stress given during the ripening period, using 96 old and new varieties developed all over Japan. By the early-season culture, the plants were exposed to a higher temperature for 40 days after heading (ripening period) than in the normal-season culture. The percentage of highquality grain and 1000 kernel weight was lower in the early-season culture than in the normal-season culture. White-bucked rice and/or milky-white rice mainly caused the deterioration of grain quality. Most varieties developed recently in Hokuriku region showed less deterioration of grain quality caused by the high temperature during the ripening period. These facts suggest that, in the Hokuriku region, rice breeding has been conducted in a high temperature condition after heading resulting in the selection of varieties with high tolerance to the high temperature after heading. In particular, Koshihikari, Koshijiwase, Fukuhikari, Fukuhonami and Yukinosei were highly tolerant varieties. These varieties are all relatives of Koshihikari. Both types with high and low tolerance types to the high-temperature stress in grain quality are included in the old and new varieties developed in the regions except for the Hokuriku region. Consequently, it was suggested that tolerance to the high-temperature stress after heading is genetically controlled and it is very important to select the cross combination, particularly for the development of the varieties to be cultivated in the early-season culture.