Arterial spin labeling (ASL) perfusion MRI has seen rapid developments during recent years. The combination of high magnetic fields, array receive coils, novel labeling and image acquisition schemes have brought ASL to the frontier of clinical applications. ASL has proven useful in clinical diagnosis of stroke, tumor, arteriovenous malformation (AVM), neurodevelopmental and neurodegenerative disorders. Alternative applications of ASL include dynamic MRA, vessel selective labeling, functional and pharmacological MRI. In addition to brain imaging, ASL can be used for perfusion imaging of body organs. Future ASL developments include ultrahigh magnetic field and the translation to clinical practice.