Abstract: We studied the effect of temperature on the uppermost internode elongation of thermosensitive-genic male sterility (TGMS) rice with the elongated uppermost internode (eui) gene. TGMS rice Shuangdi Pei eS, possessing the eui gene, was studied under the conditions of natural ecology and different artificial temperature, with Peiai 64S used as a control. We found a significant negative correlation between panicle exsertion and average diurnal temperature before heading days 12–17 (from pollen mother cell formation to meiosis). The panicle neck of Shuangdi Pei eS exserted from the flag leaf sheath under the condition of constant artificial treatment with 18°C–26°C and was enclosed in the leaf sheath at 28°C at the temperature-sensitive stage. Under pollen fertile temperature (20°C) and pollen sterility temperature (24°C), the contents of endogenous gibberellin A₁, indole acetic acid and zeatin riboside of the uppermost internode were significantly higher in Shuangdi Pei eS than in Peiai 64S, whereas that of abscisic acid was lower in Shuangdi Pei eS than in Peiai 64S; the number of innermost parenchyma cells in the uppermost internode were 1 177 and 823 higher, respectively, in Shuangdi Pei eS than in Peiai 64S, and the length was 23.2 and 16.7 μm longer, respectively. The cell division and especially cell elongation of the innermost parenchyma cell induced the elongation of the uppermost internode in Shuangdi Pei eS. Also, the number of innermost parenchyma cells was reduced in the uppermost internode and the cell length was shortened with increasing temperature. The eui gene in rice might adjust the balance among endogenous hormones to control the uppermost internode elongation of the TGMS eui mutant.