MRI has become a key tool in longitudinal monitoring of patients with MS, including assessment of brain and spinal cord atrophy. Brain atrophy measurements are emerging as sensitive surrogate markers in therapeutic trials in MS. Some recent studies have shown that brain atrophy progresses significantly on an annual basis and bears a close relationship to clinical impairment. This presentation will help the practicing neurologist better understand the methods for quantifying regional and whole-brain atrophy in MS