Abstract [Objective] This study aimed to investigate the genetic variation of wild and cultivated populations of Castanopsis hystrix. [Metbodl Genetic variation of five wild populations and three cultivated populations of Castanopsis hystrix, was investigated with ISSR-PCR amplification. Totally, 151 individuals were selected and analyzed by amplification using nine pairs of ISSR primers screened. [Result] Each primer pair produced 7-20 bands and 122 polymorphic bands were obtained. At population lev- el, ISSR diversity in the wild populations （P=59.84%, H~：~=0.182 7, /=0.285 6） was higher than which in cultivated ones （P=54.87%, H~：~=0.136 6, and /=0.219 8）. The genetic differentiation coefficient among wild populations （GsT） was 0.99. The similar population structure was found in three cultivated populations （Gsr=0.127 5）. Accord- ing to the UPGMA cluster analysis, the genetic distance among wild populations be- came larger with the increase of geographical distance. [Conclusion] Compared with other seed plants, with either a similar life history or various breeding system at- tributes, relatively low level of genetic diversity was observed in these five wild pop- ulations, which was caused by population size reduction and habitat fragmentation related to human activities. The formation of population structure may be explained by the species＇ breeding system.