Background and Objectives : Overt and subclinical hypothyroidism is associated with developing atherosclerosis and adverse changes in blood lipid. There is no data regarding the effect of normal range of thyroid hormone on the presence of coronary atherosclerosis. Subjects and Methods : We studied 125 consecutive patients (60.0짹11.1 years, male : female = 84 : 41) who underwent diagnostic coronary angiography. The clinical diagnoses on admission were stable angina (32.0%), unstable angina (53.6%), acute myocardial infarction (14.4%). Thyroid hormones [thyroid stimulating hormone (TSH), free thyroxine, free 3-iodothyronine], serum lipid levels, high sensitivity C-reactive protein (hsCRP), homocysteine and fibrinogen were measured. Coronary angiographic results were compared with laboratory findings. Results : The angiographic diagnosis of coronary artery disease was no significant stenosis in 41 (32.8%), single vessel disease in 47 (37.6%) and multivessel disease in 37 patients (29.6%). Serum TSH levels showed a trend toward higher levels in patients with multivessel disease compared no significant stenosis (1.22짹0.96 uIU/mL vs. 0.73짹0.53 uIU/mL, p=0.053). According to the levels of TSH (<1.0 uIU/mL and ���1.0 IU/mL), the incidence of multivessel disease was significantly higher in patients with high serum TSH levels (23.1% vs. 40.0%, p=0.038). A significant correlation was observed between levels of TSH and monocyte count (r=0.251, p=0.005), hsCRP (r=0.208, p=0.023) and homocysteine (r=0.279, p=0.002). Conclusion : The high level of serum TSH is associated with multivessel disease, abnormal inflammatory markers and high homocysteine levels.