Muscle imaging has been used largely as an adjunct in the assessment of patients with muscle disease and has been reported in descriptive terms only. Developments in computer-based image analysis techniques applied to muscle have enabled the quantification of muscle images using ultrasonography, computed tomography and magnetic resonance techniques. In conjunction with physiological measurements of muscle force, accurate determinations of muscle section area have allowed the determination of force per unit of cross-sectional area. This important measurement is essential if therapeutic approaches in muscle disease are to be adequately assessed. In this review the uses and merits of different imaging techniques are described with reference to new developments in quantitative analysis of muscle images and the possible utilisation of these techniques in neuromuscular disease is discussed.