The esterase isozyme of several legume plants were separated and visualized by horizontal starch gel electrophoresis using enzyme-specific staining. Extracts used were prepared from fully expanded young leaf and stem of six legume species which were red clover(Trifolium Pretense L.), ladino clover(Trifolium repense L.), wild white clover(Trifolium repense L.), alfalfa(Medicage sativa L.), mimosoides(Cassia mimosoides var nomame Makino), and amoena(Vicia amoena Fisch). The number of band, Phenotype and staining intensity of esterase isozyme in leaf and stem varies depending on the plant species. However, there are little difference between leaf and stem esterase isozyme in same species except alfalfa. And in the leaf and stem of mimosoides and amoena showed not any esterase(Fig. 2). Among the examined plants, the highest staining intensity and the rapidest migrating esterase isozyme was Est 1.