MRI/MRS can produce information on over 40 physico-chemical parameters regarded as biomarkers of structural, functional or metabolic significance. Though of undisputed worth in the detection of macroscopic lesions or of metabolic derangements, MRI’s use in prognosis and prediction has not been so extensively studied. Serial studies can be performed to show early pre-clinical changes in biomarkers caused by disease progression or therapy, such as the adverse effect on heart function of certain cancer therapies. It can utilise various haemodynamic measures to predict the evolution of stroke and so help justify certain interventions. Changes in cerebral metabolite concentrations or the volumes of brain sub-structures can be used as objective measures of drug response in psychiatric conditions. However care must be exercised as MR can sometimes be considered ‘too sensitive’ as it often detects real abnormalities even in asymptomatic volunteers, the actual predictive significance of which have yet to be fully assessed.