Thyrotropin (TSH), thyroxine (T24) 3,5,3403 triiodothyronine (T23), serum lipid levels and ECG findings in females who underwent thyroidectomy 2-44 years earlier, were compared to those of similar controls with intact thyroid. Pathological ECG is more frequent in thyroidectomized persons who also exhibit higher thyrotropin and lower HDL-cholesterol levels. The results indicate that thyroidectomized state should be regarded and controlled as a possible condition of subclinical hypothyreosis, being a risk factor of cardiovascular diseases.