Ablative radioiodine therapy is the main standard treatment for patients with differentiated thyroid cancer after total thyroidectomy. After radioiodine therapy, more than 70% of the radioiodine is excreted in urine. In patients with end-stage renal disease (ESRD) and anuria, the biological half-life of radioiodine increases and patients might accumulate more of the radiation dose. Radioiodine is removed by hemodialysis in patients with ESRD. However, there have been not many studies on radiation safety and removal of radiation activity in patients with ESRD. A 49-year-old female patient with ESRD who received 70 mCi 131I was the subject of investigation and a 24-year-old female patient with normal renal function was recruited as the control for comparison. A portable dosimeter was placed on the anterior chest wall to detect radiation changes at 4-hour intervals. After 3 days of hospital isolation, the patients were discharged. The patient with ESRD received a hemodialysis session on the day she was discharged and the radiation dose was checked every hour. During hospitalization, the immediate radiation dose in the patient with ESRD decreased much more slowly than that in the patient with normal renal function. Hemodialysis decreased the estimated radiation dose accumulation by about 60%.