In this study, we set out to evaluate the costs and effectiveness of the 2 most used therapies in our region, ATD or RAI. 23 patients, 6 men and 16 women, with a mean age of 35.4 years, treated with ATD, and 35 patients, 5 men and 30 women, mean age of 39.4 years, treated with RAI, were studied. After 2 years receiving ATD, 21 patients achieved euthyroidism and 2 remained hyperthyroid. In the RAI group, 21 patients presented hypothyroidism and 13 became euthyroid. To calculate the costs of each therapy, we analyzed the number of visits during this period, the laboratory data and the drugs needed, such as tiamazol and/or thyroxine. The group treated only with ATD needed a higher number of visits and laboratory measurements, with the mean total cost of R dollars 1,345.81, while the RAI group spent a mean amount of R dollars 622.94. Therefore, the costs of the RAI treatment were 53.5% lower than clinical therapy with ATD. The present study demonstrates that RAI treatment has a lower cost than ATD, being very effective in controlling the hyperthyroidism of Graves disease.