Primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) achieves brisk coronary flow in > 90% of patients, but myocardial reperfusion (reperfusion at the tissue level) is often suboptimal, as evidenced by persistent ST-segment elevation and abnormal myocardial blush. Patients with suboptimal myocardial reperfusion have limited myocardial salvage and increased mortality. Distal micro-embolization may contribute to poor myocardial reperfusion, and this has stimulated great interest in the use of adjunctive thrombectomy with primary PCI in an attempt to prevent distal micro-embolization and improve outcomes. In this paper, we review the randomized trials that have evaluated the use of adjunctive thrombectomy with primary PCI using three types of devices (X-sizer, aspiration thrombectomy and rheolytic thrombectomy). The results of these trials have been conflicting and the totality of evidence does not support the routine use of thrombectomy for removal of thrombus in patients with STEMI treated with primary PCI. In patients with large thrombus burden, distal macroembolization is common and is associated with poor outcomes. Adjunctive thrombectomy can effectively remove thrombus, and it seems appropriate to perform adjunctive thrombectomy prior to primary PCI in patients with large thrombus burden.