The levels of high temperatures (35, 38 and 41 degrees C in 7 day/night) used in this study and decreased or delayed the germination of maize, rice and sorghum seeds. Growth regulator pre-treatments (especially GA(3)) decreased this inhibitive effect of the high temperature to a great extends at 35 and 38 degrees C in maize and rice seeds. In generally, no significant differences were detected between the control and kinetin treatments in maize and rice at 41 degrees C. GA, increased rapidity germination and stimulated seed germination at all using temperate treatments in species. The case of sorghum for rapidity and final seed germination, plant growth regulators were effective thermal treatments at 38 degrees C and over temperature. The high temperature was shortened the elongation of radicle and coleoptile and prevented at 35, 38 and 41 degrees C. GA, enormously maintained its stimulative effect observed on the coleoptile and radicle emergence and elongation except at 41 degrees C in rice. KIN had the lower the elongation of radicle when averaged across the GA(3) and control at high temperature conditions in all species.