Aim: Thyroid dysfunction is common among older people associated with morbidity and mortality. Overall, the most common cause of hyperthyroidism is Grave's Disease (GD). In the older population however, Toxic Multinodular Goitre (TMG) is more common. Iodine is an essential molecule for thyroid hormone synthesis. This may be due to the presence of autonomic areas with a higher sensitivity to iodine in the thyroid gland. The aim of this study was to detect the etiology of hyperthyroidism among cases older than 60 years. Material and Method: The study included 100 patients = 60 years or older with hyperthyroidism. Demographic and clinical features of the patients were recorded. All patients were tested for anti-thyroid autoantibodies and underwent thyroid ultrasonographic (USG) and scintigraphic examination. Iodine exposure was detected in 24-hour urine specimens. Results: Eightyone patients (81%) had overt and the remaining 19 (19%) had subclinical hyperthyroidism and the mean age was 70.48 +/- 6.16 (range 60-88). Thirteen patients had recent exposure to iodine and 11 had Jod Basedow Phenomenon (JBP). The most common disease was TMNG (29.2%) and 8 patients had no definitive diagnosis; they were designated nondiagnostic (ND). Discussion: This is the first study that investigates the causes of thyrotoxicosis amoung older people in our country. The results indicated that TMNG was the most common cause. JBP cases had a history of exposure to iodine. For this reason, radiocontrast use in older people should be carefully evaluated with this respect.