Coronary artery ectasia (CAE) is a variant of coronary atherosclerosis. Mean platelet volume (MPV), an indicator of platelet activation, has been shown to be elevated in patients with acute coronary syndromes and myocardial infarction in the setting of obstructive coronary artery disease. The aim of this study was to assess the MPV in patients with CAE. We retrospectively studied 366 consecutive patients with CAE (195 men/171 women; mean age 55.4 +/- 10.9 years) and 160 control patients (81 men/79 women; mean age 53.5 +/- 10.2 years). MPV values were recorded in all study and control patients. The MPV values of patients with CAE were found to be significantly higher than those of the controls (9.2 +/- 1.1 versus 8.8 +/- 1.2 fI, respectively; P<0.001). The platelet count was detected to be significantly lower in patients with CAE group than in patients with control group (233.7 +/- 70.7 versus 264.7 +/- 102.8 (x10(9)/I), respectively; P<0.0001). We have shown that MPV was significantly elevated in patients with CAE compared with controls. Blood Coagul Fibrinolysis 20:321-324 (C) 2009 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.