The objective of this study is to evaluate the role of thyroid stimulating hormone receptor antibodies (TSHRAb) in the diagnosis of Graves’ disease and the differentiation between Graves’ disease and other causes of hyperthyroidism. TSH receptor antibodies were assessed in 62 thyrotoxic patients, and proved to be positive in 30 cases, borderline in 16 cases and negative in 16 cases. All patients were subjected to thyroid scan using 5 mci of Tc-99m pertechnetate. Among 37 patients with diffuse uptake 23 cases have positive Anti-R-TSH level while 4 cases have negative level with high statistical significance. Out of 17 cases with nodular uptake, 9 cases have negative Anti-R-TSH level and only 3 cases have positive level with high statistical significance. Negative anti-R-TSH antibodies were observed in 100% of patients with thyrotoxicosis in early thyroiditis and in 4 out of 5 patients with autonomous toxic nodule with high statistical significance.