Abstract: Objective To analyze the risk factors of thrombogenesis in the elderly population through functional tests of platelet aggregation. Method Tests of the maximum aggregation rate (MAR）and average aggregation rate (AAR) were carried out in 134 old persons. The impact of the age,gender,GLU and LDL on MAR and AAR and the value of their difference was analyzed. Results The ratio over 80 percent of MAR value was 39.6%,which is obviously higher than that (14.3%) in the control,and the ratio in females was higher than that in males (P<0.05). The median difference (3.90) of females was lower than that of males (4.85). No impact of blood glucose (P>0.05) but marked influence of LDL（P<0. 01）was noted on the abnormal value of MAR. Additionally,the value of LDL was closely correlated with the difference of MAR-AAR（R=-0.824,P<0.05）. Conclusion The risk factors of age,gender,as well as LDL level have notable impact on platelet aggregation.

Key words: MAR, Pletlet aggregation, Risk Factors