Myositis-specific autoantibodies (MSAs) are found in almost half the patients with an idiopathic inflammatory myopathy (IIM). Several clinical and epidemiological studies have suggested that MSAs are associated with specific clinical characteristics. Some of these associations are well-defined and are of clinical significance ( eg, anti-Jo-1 and the anti-synthetase syndrome), others are less well established and can cause unnecessary anxiety for both patients and physicians ( eg, anti-SRP and cardiac involvement). In this review, an overview is given of the various MSAs, their biochemical background, their clinical usefulness, and the promises they hold for a better understanding of IIM.