Occurrence of layering clumps and regeneration pattern of hiba (Thujopsis dolabrata var. hondai) in a Quercus mongolica var. grosseserrata and T.dolabrata var. hondai forest was investigated on the basis of isozyme variations. Six isozyme loci encoding five enzyme systems were used to obtain a total of 66 multilocus genotypes (MLG) throughout the whole samples of saplings and stand trees. The distributional pattern of saplings or stand trees in each MLG group was analyzed. In the ridge site, a part of the MLG groups showed random distribution while the remaining groups exhibited aggregated distribution. In the slope site, almost all MLG groups showed aggregated distribution which suggests that layering clumps exist as distributional unit. A number of MLG groups of stand trees in the slope site also manifested aggregated distribution. However, the distributional overlap between saplings and stand trees of the same MLG was unclear. It is certain that layering clumps had contributed to the regeneration of hiba in the stand. In such layering clumps, a small number of saplings would have developed into stand trees and the remaining usually would withered and died.