A novel spontaneous chlorina mutation of wheat (Triticum aestivum L.) was found in 2000. Three types of phenotypes, i.e., green plant, intermediate yellow-green plants (or chlorina), and yellow plant (aurea), were observed in the selfed progenies of the mutant. The aurea plants usually died before heading stage, and the intermediate plants were viable but less vigorous and developed later than the green plant. The mutant wheat was analyzed genetically after self-pollination and crossing with normal green plants. Selfing the M1 plant (chlorina) results in 1:2:1 segregation ratio of aurea:chlorina:green plants. The progenies of M1 green plants were all green. The test cross between a chlorina plant and a normal plant (as male or female) gave a 1 normal green: l yellow-green segregation ratio. The result can be explained on the assumption that the aurea is homozygous for au and the chlorina heterozygous for Au. Based on these findings, this mutant is controlled by a partial dominant nucleus gene. The genotypes of aurea, chlorina, and normal plants are au/au, Au/au, and Au/Au, respectively.