Subarachnoid hemorrhage is a very rare complication of thrombolytic therapy. We report the case of a 76-year- old mestizo woman with a pacemaker, admitted to the emergency room due to compromised consciousness, walking difficulties and dysarthria. She reported a history of poorly controlled hypertension, hypothyroidism, and numerous surgical interventions. Based on a non-contrast Multislice Computed Tomography (MSCT) of the brain and the clinical manifestations, a diagnosis of ischemic stroke was established. Thrombolytic therapy with alteplase was immediately started and another non-contrast MSCT brain scan, performed three hours later, identified a subarachnoid hemorrhage as a treatment complication. Twenty-four hours later, a CT angiography confirmed an ischaemic stroke with hemorrhagic transformation, without the presence of a ruptured aneurysm. The patient was admitted to ICU, remai...