Abstract: Cytoplasmic male sterility (CMS), a maternally inherited trait, is widespread among plant species. Because of the importance of CMS in hybrid seed production, understanding the molecular basis of CMS and its restoration is critical for better utilization of heterosis in crops. A number of CMS and restorer genes have been isolated, and the molecular mechanisms for the CMS-restoration interaction of some systems have been elucidated. In this paper, we review the progress in study of CMS and restorer genes in plants.