Abstract: Objective To investigate the clinical results of the coronary artery bypass grafting (CABG) for coronary artery disease (CAD) patients with completed hypothyroidism. Methods Twentyone CAD patients with hypothyroidism (hypothyroidism group) operated by a single surgeon from September 2002 to June 2009 in our department were enrolled in this study. Among them, there were 6 males and 15 females. Their average age was 60.4 years old. Three patients underwent CABG with onpump beating heart; one underwent CABG with onpump arrested heart; and 17 patients underwent CABG with offpump beating heart. All patients on thyroxine replacement therapy underwent CABG after free triiodothyronine（FT3）,free thyroxin（FT4）, thyroidstimulating hormone（TSH）, total triiodothyronine（TT3） and total thyroxin（TT4） were obviously improved. At the same time, twenty CAD patients without hypothyroidism were chosen as the control group (control group). Among them, there were 6 males and 14 females with an average age of 62.1 years old. The data of thyroid gland function and clinical prognostic indicator were observed after the operation. Results For the hypothyroidism group, one patient with pericardial effusion, heart failure and low thyroxine before surgery died during the onpump operation. Among the 20 survivors who had undergone CABG with beating heart, 17 were offpump CABG patients. Followup was done for 230 months. Postoperative eject factor of the survivors were significantly higher than their preoperative eject factor (55%±21% vs. 48%±17%). Twenty patients in the control group all survived. There was no significant difference in cardiac index ［2.7±1.4 L/(min·m2) vs. 2.8±1.5 L/(min·m2), t=0.530, P=0.530］, hospital stay (12.2±4.7 d vs. 10.1±3.9 d , t=0.170, P=0.170), or mechanical ventilation time (17.6±9.1 h vs. 15.1±13.7 h, t=0.120, P=0.120) between the hypothyroidism group and the control group. Perioperative thyroxine examination showed that there was no profound impact on thyroxine by offpump CABG. Conclusions With full preparation made before operation, CABG with beating heart is comparatively safe for CAD patients with hypothyroidism. The key of the treatment is perioperative thyroxine replacement therapy. There is much risk to perform onpump CABG on patients with severe hypothyroidism.