Abstract: Multiple sclerosis (MS) has traditionally been considered to be primarily an inflammatory demyelinating disorder affecting the white matter. Nowadays it is recognized as both an inflammatory and a neurodegenerative condition involving the white and grey matter. Grey matter atrophy occurs in the earliest stages of MS, progresses faster than in healthy individuals, and shows significant correlations with cognitive function and physical disability; indeed, brain atrophy is the best predictor of subsequent disability and can be measured using magnetic resonance imaging (MRI). There are a number of MRI methods for measuring global or regional brain volume, including cross-sectional and longitudinal techniques. Preventing brain volume loss may therefore have important clinical implications affecting treatment decisions, with several clinical trials now demonstrating an effect of disease-modifying treatments (DMTs) on reducing brain volume loss. In clinical practice, it may therefore be important to consider the potential impact of a therapy on reducing the rate of brain volume loss. This article summarizes the knowledge on brain volume in MS.Abstract: Multiple sclerosis (MS) has traditionally been considered to be primarily an inflammatory demyelinating disorder affecting the white matter. Nowadays it is recognized as both an inflammatory and a neurodegenerative condition involving the white and grey matter. Grey matter atrophy occurs in the earliest stages of MS, progresses faster than in healt...Show More