Acute vertebrobasilar occlusions (VBO) are dramatic clinical events with a mortality of up to 90% under standard medical treatment. If VBO is suspected a diagnosis of the vessel status has to be achieved immediately. For this purpose CT/CTA and MRI/MRA are equivalent diagnostic tools in the emergency setting. In contrast to the anterior circulation, local endovascular treatment is the established therapy for the posterior circulation as an underlying arteriosclerotic stenosis remains in 50% of the cases after intravenous fibrinolysis. Nevertheless, systemic fibrinolysis is considered the preferred option in cases where a neurointerventional center cannot be reached within a reasonable time frame and the patient can subsequently be transported for local therapy of a residual stenosis in order to prevent reocclusion ("drip and ship"). Profound clinical and pathophysiological knowledge is the absolute prerequisite for the correct application of state-of-the-art neurointerventional therapy. This review paper focuses on the clinical and pathophysiological details that are crucial for decision-making.