Althought allelopathy has been cleary established for Pinus densiflora by Lee-Monsi, the auther suspected that Miscanthus sinensis which grows vigrously in such Korean pine forests might also exhibit the phenomenon. A total of 33 species having an affinity in the Miscanthus group were recorded in the filed. Out of these, five species; Patrinia scabiosaefolia, Lespedeza crytobotrya. Oenothera odorata, Raphanus sativus var. acanthiformis, and Zoysia japonica were considered the "A" group. Five other species which have no affinity to Misanthus sinensis, Amaranthus patulus, Solanum nigrum, Capsella bursa-pastoris var. triangularis, Chemopodium album var. centrorubrum and Alopeculus amurensis were considered the "B" group. Extracts of Miscanthus sinensis were applied to determine relative germination and growth. It was found the growth in the "B" group was promoted by a cold water extract of Miscanthus stems and leaves, but inhibited remarkably by an extract obtained by passing cold water through Miscanthus root. As expected, growth in the "A" group was promoted by both experimental treatments.romoted by both experimental treatments.