Psychiatric disorders, such as depression, anxiety, mania, emotional lability, and psychosis could be seen in hyperthyroidism but depression is reported to be the most common psychiatric disorder such as in hypothyroidism. Although depression is associated with the slowdown behavior in hypothyroidism, an agitated depression is seen in hyperthyroidism. Psychotic reactions are not common in hyperthyroidism and often seen as a symptom of affective disorders. Here we report two patients who were admitted to psychiatry clinic with the complaints of restlessness, insomnia, loss of appetite, fear, delusion of persecution and reduction in speech. Psychiatric disorders were not noticed from the patients’ medical and family histories. Detailed physical and laboratory examination revealed disorder of thyroid function associated with hyperthyroidism. The reported cases showed the relation between thyroid disease and psychotic depression.