Objective To determine the therapeutic effect of 131 I on lymph node metastases from differentiated thyroid cancer (LMDTC) in elder patients. Methods Thirty three elder patients with lymph node metastases from differentiated thyroid cancer were received 131I therapy. The therapeutic effect was assessed comprehensively by detection of neck ultrasonography, computed tomography (CT) , whole body 131I scan and serum thyroglobulin (Tg) changes. Results LMDTC were eliminated and minimized in 27 patients. The effective rate was 81.8%. Conclusion 131I therapy is effective for elder patients with LMDTC．