There are relatively few circumstances wherein the assay of TRAb, as TSAb or TBIAb, is merited in the routine clinical management of patients with autoimmune thyroid disease. These include: 1. the prediction of neonatal hyperthyroidism; 2. the confirmation, by assay of maternal serum, and perhaps newborn blood, that neonatal hypothyroidism, identified on routine screening, may be transient and due to transplacental passage of TBIAb; 3. the prediction of relapse of hyperthyroidism at the end of a course of antithyroid drugs; this information should lead to more careful observation to identify relapse as early as possible; 4. the confirmation that adult agoitrous hypothyroidism reflects the effect of an antibody (TBIAb) blocking the action of TSH although, as discussed, there is little, if any, practical gain from this information. Additional applications of the routine use of TRAb assays will require the development of a procedure that combines the sensitivity, specificity, availability, and ease found variably in current TSAb and TBI procedures, and at much less cost than what is provided today.