After evaluation of antithrombotic effect of 40 herbs on platelet aggregation induced by ADP(Adenosine diphosphate), these results were obtained as follows: 1. Crude drugs exerting over 30 % of in Chinemys reevesii (Gray)hibition on platelet aggregation induced by ADP were Ganoderma japonicum (Fr.) Lloyd., Panax ginseng C. A. Mey., Gastrodia elata Bl., Thea sinensis, Chinemys reevesii (Gray), Cuscuta chinensis Lam., Cervus nippon Temminck., Biota orientalis (L.) Endl., Coriolus versicolor, Cinnamomum cassia Presl., Sophora flavescens Ait., Amomum villosum Lour., Carthamus tinctorius L., Rubus chingii Hu., Poria cocos (Schw.) Wolf., Laminana japonica Aresch., Ligustrum lucidum Ait., Angelica sineusis (Oliv.), Cyperus rotundas L., Ginkgo biloba L., Zingiber officinale Rosc., Prunus persica (L.) Batsch., Schizandra chinensis (Turcz.) Baill. and Plantago asiatica L.. 2. Of crude drugs having showed over 50% of inhibitory effect on platelet aggregation, at the concentration of $100{\mu}g/m{\ell}$, the inhibitory rates were 82.2% in Ganoderma japonicum (Fr.) Lloyd., 55% in Panax ginseng C. A. Mey., 50.8% in Gastrodia elata Bl., while at the concentration of $200{\mu}g/m{\ell}$, antithrombotic rates were 89.4% in Ganoderma japonicum (Fr.) Lloyd., 59.2% in Panax ginseng C. A. Mey., 57.9% in Thea sinensis, 52.7% in Gastrodia elata Bl.. These results suggest that the study sholuld be necessary on antithrombotic effect of solvent fractions of Ganoderma japonicum (Fr.) Lloyd., Panax ginseng C. A. Mey., Gastrodia elaha B1. and Thea sinensis and isolation of effective compound from above drugs.