Objective: The aim of the study was to investigate the effects of short-term overt hypothyroidism on lipids after thyroxine-withdrawal in patients with iatrogenically induced hypothyroidism before radioiodine treatment for differentiated thyroid carcinoma (DTC). Methods: Thirty patients with a history of differentiated thyroid carcinoma on thyroid-stimulating hormone (TSH)-suppressive thyroxine replacement therapy were studied. Blood sample were taken before and 4 weeks after withdrawal of thyroxine substitution. Venous blood was drawn after an overnight fast and analyzed for serum free T4 (FT4), free T3 (FT3), thyroid-stimulating hormone (TSH), total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB). Fifty healthy people matched for age and gender were controls. Their blood samples were taken only once. Results: After thyroxine-withdrawal, the patients presented with increased serum TSH and low serum FT4 and FT3 levels compared with controls. Serum TG, TC, LDL, HDL, ApoB and Lp(a) increased after thyroxine withdrawal, reaching statistical significant differences with previous evaluation. However, when compared to euthyroid controls, only TC, LDL and ApoB were increased when patients were hypothyroidism. No changes were observed in ApoA1 in patients during thyroxine withdrawal, or when comparing the values observed in patients to those of euthyroid controls. Conclusion: TG, TC, LDL, HDL, ApoB and Lp(a) were increased during short-term overt hypothyroidism.