Of the twelve chromosornes, chromosorne 12 have not corresponded to any linkage group. This study was carried out to make clear the correspondence between the twelve chromosomes and the linkage groups. The extra chromosorne of trisomics D was identified as chromosome 12 since the pentavalent formation was observed in PMCs of F₁ hybrids betvveen the trisomics and reciprocal translocation lines involving chromosome 12. Observation on the F₂'s from the crosses between the trisomics D and two genes, su and newly found virescent seedling, v-8(t), showed trisomic segregation. These results lead to the conculsion that the genes located on chromosome 12 constitute a new linkage group. The complete relationship between twelve chromosomes and linkage groups in rice has established.