For patients suffering from acute ischemic stroke from cerebral artery occlusion, reperfusion is necessary to save the ischemic penumbra. Therefore, early and complete recanalization of an occluded artery is the main therapeutic goal of acute ischemic stroke. Among the many advances in management of acute ischemic stroke, thrombolysis with intravenous (IV) tissue plasminogen activator (t-PA) within 4.5 hours after symptom onset has been the only approved pharmacological therapy. However, IV t-PA has many limitations in clinical practice, low eligible patients and low recanalization rates, particularly in cases of larger proximal artery occlusions. In addition, there are many complications, including symptomatic intracranial hemorrhage (approximately 6%). In contrast, higher recanalization rates and an extended therapeutic time window have been reported for intra-arterial (IA) thrombolysis. According to studies until 2013, no studies proving the advantages of IA thrombolysis have been reported. However it was reported that studies in 2015 showed its possibility. Therefore, the purpose of this article is to cast a light on failures of previous studies, and try to assess the differences with studies in 2015. In addition, crucial points for successful IA thrombolysis will be discussed.