Abstract: Number of nucleolar chromosomes of indica and Japonica rice and their hybrids bad been studied during 1985-1986. The results indicated that the cell of indica rice bore two nucleolar bivalent chromosomes at diakinesis, but that of Japonica rice bore one. The number of nucleolar chromosomes of hybrids between indica and Japonica rice had similarity to their male Parents. Therefore, we had strongly suggested that amphiplasty had great significance for rice breeding, origin and genetics.