Introduction. Systemic thrombolysis is a generally recognized highly eff ective treatment for ischemic stroke. Malignant cerebral infarction (MCI) in the territory supplied by the middle cerebral artery is characterized by a lesion affecting 50 % or more of the vascular territory therefore acting as a contraindication to systemic thrombolytic therapy. At the same time, when admitted to the hospital during the therapeutic time window, some patients with MCI remain candidates for systemic thrombolysis until an infarcted focus is identifi ed in the area supplied by the middle cerebral artery (MCA). Purpose of the study: to assess the eff ectiveness of intravenous thrombolytic therapy in patients with occlusion at the proximal segment of the middle cerebral artery. Material and methods: the study was conducted among 75 MCI patients, 9 of them received intravenous thrombolytic therapy (IVTT), in one case it was combined with endovascular mechanical thrombectomy. One patient underwent surgery (decompressive hemicraniectomy) after ineff ective intravenous IVTT. Results: intravenous thrombolytic therapy and/or endovascular mechanical thrombectomy performed for patients with occlusion of the M1 segment of the MCA did not prevent the natural development of extensive ischemic damage and edema of the cerebral hemisphere in patients with occlusion of the proximal MCA segment. In 20 % of the patients, intracerebral hemorrhage developed. A fatal outcome following IVTT occurred in 30 % of patients; it was caused by increasing swelling of the cerebral hemisphere and the development of dislocation syndrome. Conclusion: intravenous thrombolytic therapy and/or endovascular mechanical thrombectomy performed in patients with occlusion at the proximal segment of the MCA does not prevent the natural development of extensive ischemic damage in the cerebral hemisphere (MCI).