Abstract: 3,4-Dihydroxyacetophenone(DHAP)is one of the constituents of Ilex pubescence Hook.et Arn.var.glaber Chang.The effects of DHAP on the composition of blood plateletmembrane in aged rats was examined.No change of total lipid and cholesterol contents was observedin aged rats.While a slight but significant decrease of phospholipid in platelet membrane was found,which lead to diminution of the ratio of phospholipid to cholesterol.The contents ofphosphatidylethanolamine and phosphatidylcholine decreased markedly by as less as 23.0%and 19%,respectively ,compared with the young group.Whereas the degree of reduction of phospholipid ,theratio of phospholipid to cholesterol,phosphatidylethanolamine and phosphatidylcholine weresignificantly lightened after irrigation with DHAP 100 mg· kg^-1 for 10 weeks.In the treatmentgroup ,the values of phosphatidylethanolamine and phosphatidylcholine of platelet membrane werereduced by 8.0%and 10.5%, respectively,vs the group of aged rats.It is concluded that reducedphospholipid hydrolysis is involved in mediating DHAP inhibition of platelet function.