Aneuploids of sugi (Cryptomeria japonica) were found in the open-pollinated progenies of triploidplus tree clones. Seven trisomics and one hypotriploid were used to assign the chromosomes to the RFLP linkage groups constructed previously. The Southern blots containing their genomic DNA were hybridized with the labeled DNA clones corresponding to the loci in the linkage map. The additional dosage in autoradiographs showed that the cloned DNA fragment was located on the extra chromosome in the trisomics. On the other hand, the extra chromosome in two trisomics and the chromosome lacking the triplet in the hypotriploid were cytologically identified as chromosome 10 by consistent presence of a secondary constriction in the proximal region of its short arm. As a result, three linkage groups were assigned to their respective chromosomes, namely chromosome 10 and two other chromosomes.