Iodine-induced thyrotoxicosis is a life-threatening disease. Plasma exchange and hemoperfusion are the available means of detoxication. Both methods were applied repeatedly to 4 patients with iodine-induced thyrotoxicosis, and the efficacy of these treatment methods was compared. Thyroxine plasma levels were decreased by 33%, while the calculated body stores were reduced by 18% during plasma exchange. Hemoperfusion was less effective. With both methods, a rebound of plasma levels was seen. Improvement of the clinical condition was delayed for 1 week after discontinuation of treatment. One patient died, probably because detoxication was discontinued too soon after the thyroid hormone levels had normalized. Plasma exchange by using albumin (120 g/4,000 ml = 30 g/l) as replacement fluid is superior to that by using fresh-frozen plasma (2,000 ml/4,000 ml), since less thyroxine is administered (19 vs. 160 nmol).