Sasa borealis Makino is distributed in East Asia such as Korea, Fushun in China, and Japan. Especially the species is only found in the high altitude (above 600 m) at mountain of cold regions including The Korean Peninsula. The level of genetic diversity and population structure of this species was surveyed using starch gel electrophoresis at putative five enzyme loci from three natural populations in Korea. Results from twelve loci indicated that genetic diversity was low. In addition, analysis of fixation indices revealed a substantial heterozygosity deficiency in some populations and loci. The reasons for the deficit of heterozygosity may be partly considered inbreeding, small population sizes, and mating of demes. S. borealis can reproduce extensively by producing rhizomes and potentially by sexually produced seeds. Rhizomes are generally long, prostate stems rooting at the nodes.