A patient with papillary carcinoma of the thyroid was scanned with 10 mCi of 1–131 postoperatively before thyroablation therapy. Two weeks later, the patient was given 100 mCi of 1–131. The posttherapy scan showed very little uptake in the thyroid remnant, suggesting that the thyroid was stunned before therapy. This case was compared with another in which the patient was scanned with 1–123 followed by 1–131 therapy. There was excellent uptake of the therapy dose. Pretherapy scanning with a high dose of 1–131 may suppress the thyroid tissue and inadvertently prevent maximum uptake of a subsequently administered therapy dose of 1–131.