BACKGROUND Ischaemic heart disease is mainly caused by atherosclerosis and its complications. Platelets and their activity have an important role in initiation of atherosclerotic lesions and coronary thrombus formation. Larger platelets are enzymatically and metabolically more active and have a higher potential thrombotic ability as compared with smaller platelets. OBJECTIVE To study the changes in platelet volume indices and platelet count in ischaemic heart disease and assess their usefulness in predicting coronary events. METHODS This was a comparative study of 180 patients (60 patients with stable angina, 60 with acute coronary syndrome and 60 with non-cardiac chest pain). Blood venous sample were drawn from all subjects after admission (within 30 min) and collected in standardised EDTA sample tubes. Platelet count and volume indices were assayed within 30 min of blood collection, using Sysmex KX21-N autoanalyzer. RESULTS The platelet count was significantly lower in patients with acute coronary syndrome (201.28 x 10(9)/l) as compared with patients with stable angina (267.07 x 10(9)/l) and those from the normal population (256.65 x 10(9)/l) (p<0.001). In addition, patients with acute coronary syndrome had higher platelet volume indices (10.97) compared with patients in the stable angina (10.03) and normal population groups (9.12) (p<0.001). CONCLUSIONS Patients with acute coronary syndrome had higher platelet volume indices and lower platelet counts compared with those with stable angina and the normal population. Measurements of platelet volume indices and platelet count may be of some benefit in detecting those patients at higher risk for acute coronary events.