MRI has revolutionized the diagnosis of multiple sclerosis (MS). In addition, use of MRI has provided a means to monitor disease and the response to therapy and has been used extensively as an adjunct means to evaluate new therapies. Despite its high sensitivity to detect MS lesions, its specificity for the underlying pathology is low. Furthermore, correlation of MS disability with the extent of abnormalities using several different methods of imaging has been modest at best. This chapter discusses the main imaging techniques used for MS diagnosis, MS management and treatment monitoring, and in clinical trials.