Renal involvement in thyroid diseases is an unusual event. Antineutrophil cytoplasmic antibody (ANCA) associated vasculitis has been reported in propylthiouracil-treated patients. Membranous glomerulonephritis has been reported in association with both antithyroglobulin and thyroid antimicrosomal antibodies. The development of membranous glomerulonephritis may be associated with administration of 131I. We present a patient who developed membranous glomerulonephritis after administration of 131I. The clinical and pathological features of renal involvement in thyroid diseases are reviewed.