Patients with end-stage renal disease (ESRD) are at risk of prolonged radiation exposure during therapy with radioactive iodine (131I) because it is normally renally excreted. However, 131I is dialyzable and exposure can be monitored with a standard Geiger counter during dialysis. We present two cases of thyroid carcinoma in patients with ESRD who were treated successfully with 131I while continuing chronic hemodialysis (HD). In each case, single HD treatments of 3 and 4 hours performed approximately 20 hours after the administration of 131I resulted in an 80% and 70% reduction in total body radiation levels, respectively. In both cases, Geiger counter measurements after HD following 131I administration revealed levels less than 3 mR/hr, allowing safe discharge from the hospital in a timely manner. All contaminated waste was disposed of by the hospital's Department of Radiation Safety. Postdialysis monitoring revealed no residual radiation contamination of the HD machine or radiation exposure to the dialysis staff. Hemodialyzer reuse was suspended until monitoring demonstrated no appreciable evidence of radioactivity in these spent supplies. HD is a critical aspect in the treatment of patients with ESRD receiving 131I and can safely be administered with close planning between the HD staff and the staff of radiation safety.