Abstract: Ginkgo biloba L.is a deciduous woody plant.The female plants and maleplants have different uses.It is therefore advantageous to distinguish the sexof individual plant before at flowers. Experiments performed in 4 successive years in our laboratory show thatperoxidase isozyme patterns are sexassociated.There are more bands in theyoung leaves of the female plant than in the male.When examining theperoxidase isozyme patterns in the leaves of trees with unknown sex,wefound there exist only two types:one agrees with the male,the other agreeswith the female.There are no intermediate types. The esterase isozyme pattern has nothing to do with sexuality.It istherefore considered that peroxidase isozyme pattern can be used as abiochemical test to distinguish the sex of individual plant in Ginkgo biloba L.