Thyroid-stimulating hormone receptor autoantibodies (TRAbs) are pathogenetic and diagnostic in Graves’ Disease (GD). We briefly review the value of these antibodies in GD during diagnosis, treatment, relapse and pregnancy. Currently available methods for monitoring are immunoassays for TRAbs and bioassay and immunoassay for TSI specifically. In the last 50 years several methods have been used to detect autoantibodies against TRAbs, based on bioassays or immunoassays. The bioassays measure functional activity of TRAb; cumbersome, time consuming and unsuitable for routine use in clinical laboratories. Immunoassays measure binding of the autoantibodies to the receptor without functional discrimination, are better standardised, much less expensive, and easily automatable for routine use in clinical laboratories. We briefly discuss the latest available immunoassay with discrimination of the autoantibody, i.e. Thyroid Stimulating Immunoglobulin (TSI).