In hybrid rice development, a serious problem associated with cytoplasmic male sterile (CMS) lines is poor panicle exsertion, which reduces outcrossing rate and hybrid seed production. Gibberellic acid (GA3) has been routinely used to solve this problem. Other problems arise from application of GA3, however, including increased costs, reduced seed quality, and possible environmental hazards. Rugter and Carnahan (1981) reported a recessive mutant that can cause elongation of the uppermost internode, referred to as the eui-1gene. Since eui can play the same role as GA3 when transferred into CMS lines, this finding has attracted much interest in the development of CMS lines. We generated eui mutants through irradiation on both maintainer (B) and restorer (R) lines and transferredeui-1 into CMS lines in China to improve hybrid rice seed production efficiency (Yang 1998). We report here the discovery of a new euigene, referred to as eui-2(t), and the development of several B and R lines with the eui gene (designated as eA and eR), as well as the development of several hybrids with eui CMS lines.