In the last several years, great progress has been made in ultrasound perfusion imaging of the brain. Different approaches have been assessed and shown to be capable of the early detection of cerebral perfusion deficits in stroke patients. Real-time low-mechanical index imaging simplifies the acquisition of perfusion parameters and alleviates many of the previous imaging problems related to shadowing, uniplanar analysis, and temporal resolution. With the advent of this new, highly sensitive contrast-specific imaging technique, new possibilities of the real-time visualization of brain infarctions and cerebral hemorrhages have emerged. This review will detail the methodology of ultrasound perfusion imaging, discuss aspects of its safety and present the emerging clinical applications of brain perfusion assessment with ultrasound in acute stroke patients.