UNLABELLED Elderly patients represent a high risk category among subjects with atherosclerosis, due to the presence of comorbidities and suboptimal response to antiplatelet drugs. Mean platelet volume (MPV) has been indicated as a marker of platelet reactivity, with contrasting data on its role on coronary artery disease. Aim of the present study was to evaluate the impact of age on the MPV and its role on the extent of coronary artery disease (CAD). METHODS Our population is represented by a cohort of 3750 patients undergoing coronary angiography. Elderly were defined according to age ≥ 75 years. MPV was measured at admission. Significant coronary artery disease was defined as a stenosis >50% in at least 1 coronary vessel, while severe CAD was defined as left main and/or three-vessel disease. RESULTS A total of 1170 out of 3750 (31.2%) patients were ≥ 75 years old. Advanced age was associated with female gender (p<0.001), hypertension (p<0.001), renal failure (p<0.001), previous myocardial infarction (p=0.03) coronary artery bypass grafting (p<0.001) indication to angiography (p<0.001), therapy with angiotension-receptor blockers, (p=0.003), nitrates, diuretics and calcium-antagonists (p<0.001), serum creatinine (p<0.001), fibrinogen (p<0.001) and C reactive protein (p=0.02), but inversely to percutaneous coronary interventions (p=0.02), dyslipidemia, family history of CAD and smoking (p<0.001, respectively), use of statins (p=0.02) and beta blockers (p=0.003), haemoglobin, total cholesterol and triglycerides (p<0.001, respectively), white blood cells (p=0.009) and platelet count (p=0.006). Elderly patients displayed a significantly larger platelet volume (p<0.001), with a direct linear relationship between age and the MPV (r=0.08, p<0.001), with age being confirmed as an independent predictor of larger MPV (≥10.85fl) at multivariate analysis (adjusted OR [95% CI]=1.18 [1.01-1.40], p=0.04). Among the elderly, MPV value above the median (≥10.85fl) was not associated with a higher prevalence of coronary artery disease (77.3 vs. 79.4%, p=0.39, adjusted OR [95% CI]=0.94 [0.66-1.33], p=0.71), or higher prevalence of severe CAD (35.2 vs. 32.4%, p=0.28, adjusted OR [95% CI]=1.34 [0.99-1.82], p=0.06). CONCLUSION Advanced age was directly associated with larger mean platelet volume that, however, did not contribute to explain the higher prevalence and extent of coronary artery disease observed in elderly patients.