Magnetic resonance spectroscopic imaging (MRSI) can be used to define specific chemical-pathological changes in the brain of patients with multiple sclerosis. Magnetic resonance spectroscopy offers promise for improved definition of the nature of individual lesions, the dynamics of their evolution, their effects on normal appearing white matter, and their relation to clinical disability. Combined multimodal MRSI studies of the brains of patients with multiple sclerosis therefore soon may provide efficient, specific, and quantitative new approaches to assessment of drug effects in therapeutic trials.