Standard medical practice is to treat Graves’ disease with antithyroid drugs for 12-18 months and then to stop treatment. However, predicting who will relapse and who will remain in prolonger remission following antithyroid drugs is not robust. TRAb antibodies are predictive of relapse and these are secreted from terminally differentiated B lymphocytes, known as plasma cells. A cohort of 120 Graves’ disease patients who are about to stop taking antithyroid (thionamide) medication following at least 12 months of treatment will be recruited. Following recruitment, details of patient presentation including baseline serum thyroid function, thyroid stimulating hormone receptor antibody levels and peroxidase antibodies will be recorded. Serum and blood for DNA and peripheral blood mononuclear cells will be taken twice; immediately before stopping antithyroid drugs and 6 weeks later. Patient phenotype of remission or relapse one year after cessation of antithyroid medication will be used to categorise for analysis of B lymphocyte markers and RNA-sequencing, aiming to have up to 50 or more patient samples available per group. We will develop a predictive test that may allow us to determine which patients will remain in remission following antithyroid drugs and also allow us to understand more about the B lymphocyte biology behind remission.