Graves' disease is an autoimmune disorder that is the most common cause of hyperthyroidism. Other symptoms associated with the disease are goitre, ophthalmopathy, and psychiatric manifestations such as mood and anxiety disorders and, sometimes, cognitive dysfunction. Graves' hyperthyroidism may result in these latter manifestations via the induction of hyperactivity of the adrenergic nervous system. This review addresses the psychiatric presentations, and their pathophysiology and treatment, in patients with hyperthyroidism, based on literature identified by a PubMed/MEDLINE database search. Although the focus is on mental symptoms associated with Graves' disease, it is not always clear from the literature whether patients had Graves' disease: in some studies, the patients were thought to have Graves' disease based on clinical findings such as diffuse goitre or ophthalmopathy or on measurements of thyroid antibodies in serum; however, in other studies, no distinction was made between Graves' hyperthyroidism and hyperthyroidism from other causes. Antithyroid drugs combined with beta-adrenoceptor antagonists are the treatments of choice for hyperthyroidism, as well as for the psychiatric disorders and mental symptoms caused by hyperthyroidism. A substantial proportion of patients have an altered mental state even after successful treatment of hyperthyroidism, suggesting that mechanisms other than hyperthyroidism, including the Graves' autoimmune process per se and ophthalmopathy, may also be involved. When psychiatric disorders remain after restoration of euthyroidism and after treatment with beta-adrenoceptor antagonists, specific treatment for the psychiatric symptoms, especially psychotropic drugs, may be needed.