The effects of the environmental temperature during the early development of seeds on the characteristics of the endosperm starch were investigated using near- isogenic lines of rice plants grown under temperature controlled conditions. The components of starch and pasting characteristics of starch granules varied by the environmental temperature. The lower temperature increased the amylose content and the ratio of short chain to long chain of amylopectin. Moreover, the starch granules of rice plants grown under the lower temperature were more gelatinized than those grown under the higher temperature. By high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) of Pseudomonas-isoamylase-debranched amylopectins we found the amylopectin of Taichung 65 (waxy) grown under the lower temperature (25°C) has decreased amounts of chains with degree of polymerization (DP) of 8 and 9, and slightly increased amounts of chains with DP of 6 , 11, 12 and 13 compared with the amylopectin of the same near-isogenic plants grown under the higher temperature (30°C).