Successful management of the idiopathic inflammatory myopathies requires an early and accurate diagnosis. The muscle biopsy remains the definitive test. However, false-negative biopsy results are common, as the disease is typically patchy in distribution. The advent of short tau inversion recovery sequences now allows rapid magnetic resonance imaging of the whole body to be performed, enabling identification of the muscles most suitable for biopsy. It also provides further diagnostic information through the form and anatomic distribution of the pathology. We report 2 cases illustrating the advantages of whole-body short tau inversion recovery magnetic resonance imaging before muscle biopsy. We encourage clinicians to use the technique in this context.