Objective To detect the platelet aggregation in elderly patients with hypertension and to determine the frequency of aspirin resistance and its risk factors. Methods A total of 184 elderly patients with hypertension (91 cases in aspirin therapy group and 93 cases in non-aspirin group) and 25 normal controls were enrolled in the study. Platelet aggregation was determined by adenosine diphosphate (ADP) or arachidonic acid (AA) induction and the level of blood thromboxane B2 (TXB2) was determined by ELISA. According to the meassurements, the patients in aspirin therapy group were divided into three groups: aspirin resistance(AR) group, aspirin semiresponder (ASR) group and aspirin sensitivity(AS) group. Differences in clinical data were analyzed to find the related risk factors of AR. Results The platelet aggregation rate in non-aspirin group was higher than that in normal group[(PAgTAA: (47±15)% vs (40±17)%, P＜0.05; PAgTADP: (69±8)% vs (63±6)%, P＜0.01]. The incidence of AR and ASR was 14.29%(13/91)and 28.57%(26/91) in aspirin therapy group. The plasma TXB2 level was higher in both AR group and ASR group than in AS group [(78±5) vs (52±8) μg/L, (64±10) vs (52±8) μg/L, P＜0.01]. The plasma TXB2 level was positively correlated with PAgTAA and PAgTADP(P＜0.01). There were more diabetic patients and smokers in AR and ASR groups than in AS group(P ＜ 0.05). Logistic regression analysis revealed that AR is likely correlated with increased levels of fasting blood-glucose and low density lipoprotein (P=0.002 and P=0.044). Conclusion Elderly patients with hypertension have higher platelet aggregation rate than normal controls. The plasma TXB2 level is positively correlated with AR and may be used as biochemical test marker like platelet aggregation. The increased levels of fasting blood glucose and plasma low density lipoprotein are independent risk factors for AR in elderly patients with hypertension.