Purpose: Overt hypothyroidism affects mostly women with an increasing prevalence with age. Hypothyroidism is associated with accelerated atherosclerotic cardiovascular diseases possibly caused by the higher incidence of hyperlipidemia, insulin resistance, and hypertension. Heart-type fatty acid-binding protein (H-FABP) is specific for cardiomyocytes and a sensitive marker of myocardial injury. The purpose of this study was examining the effect of hypothyroidism on H-FABP levels and carotid artery intima-media thickness (CIMT). Material and Method: We measured serum H-FABP levels in 33 patients with overt hypothyroidism and age, gender, and body mass index-matched 39 control subjects. The patients were newly diagnosed with Hashimoto's thyroiditis. All participants underwent high-resolution B-mode ultrasonography for the measurement of CIMT. Results: There was no significant difference in serum levels of H-FABP between the patient group and controls (1515.87 +/- 2143.0 pg/mL vs. 953.0 +/- 416.0 pg/mL, respectively; p= 0.15). CIMT level was significantly higher in the patient group than in the control group (0.53 +/- 0.08 mm vs. 0.48 +/- 0.05 mm; p= 0.02). However, the homeostasis model assessment of insulin resistance and fasting insulin levels did not differ between the two groups. Discussion: Based on the results of this study, we assume that H-FABP is not a useful marker in detecting preclinical atherosclerosis in patients with overt hypothyroidism associated with Hashimoto's thyroiditis, however, CIMT might be a useful marker in detecting early atherosclerosis.