Abstract: AIM:To study the correlation between the level of serum myocardial enzyme and cardiac function in rabbits with hyperthyroid cardiomyopathy. METHODS: Thirty New Zealand purebred rabbits were randomly divided into two groups: control group (n=10) and experimental group (n=20). Animal model of hyperthyroidism was established by peritoneal injection of levothyroxine (LThy) in the experimental group. According to the ultrasound parameter changes, ventricular geometries of the experimental group were divided into two groups: concentric hypertrophy (CH) and eccentric hypertrophy (EH). Each group underwent conventional echocardiography and myocardial enzyme values were evaluated. RESULTS: In the CH group, LVMI and RWT increased in an obvious manner (P<001). In the EH group, LVMI increased in an obvious manner (P<001), whereas RWT did not change significantly. Both EF and FS in the EH group were significantly lower than those in the control group (P<001). Serum CKMB in the EH group was conspicuously higher than in the control group and CH group (P<001). Pathological examination showed that the damage in the EH group was more severe than in the CH group. LVEF and LVFS were negatively correlated with myocardial enzyme in blood (r=0393, P<005; r=0423, P<005). CONCLUSION: Serum CKMB in different geometric patterns of the left ventricle in rabbits with hyperthyroid cardiomyopathy increases to different degrees. Elevation of myocardial enzyme is associated with the degree of pathological injury and is significantly correlated with cardiac dysfunction.