The role of coronary spasm in variant angina is well established. We have studied the time course of platelet activation during Ergonivine provocation to determine one significance of platelet indices for spasm testing. The results showed that spontaneous platelet aggregates and β-thromboglobulin levels in patients with coronary vasospasm were increased during provocation and that platelet activation during a positive Ergonivine test precede ECG changes and chest pain.