Aim To explore the effect of hyperhomocysteinemia （HHcy） on the changes of myocardial enzyme spectrum and its correlation with P53 gene. Methods 36 male ApoE^―/― mice were randomly divided into 3 groups （n＝12 for each group）: AopE^-/- control group, hyperhomocysteinemia group and intervention group. They were respectively fed with nomal diet, normal diet enriched 1.7% methionine and nomal diet plus 1.7% methionine 0.006% folate and 0.000 4% vitamin B₁₂ for 14 weeks. 12 healthy 5-week-old male C57BL/6J mice were taken as normal control group. The levels of serum homocysteine （Hcy） and myocardial enzyme levels in the four groups were measured by automatic biochemical analyzer. The content of serum oxidized low density lipoprotein （ox-LDL） was detected by enzymelinked immunosorbent assay （ELISA） the protein and mRNA expressions of P53 in the heart were detected by immunohis tochemical assay and real time polymerase chain reaction （RT-PCR）. Results The content of Hcy was significantly higher in ApoE^―/― control group, HHcy group and folate treatment group than normal control group, a remarkable increase was observed in the HHcy mice （P<0.01）, the ox-LDL level showed a parallel increase with the Hcy, the difference was significant （P<0.05）. The contents of creatine kinase-MB （CK-MB）, creatine kinase （CK）, hydroxy butyrate dehydrogenase （HBDH） and lactate dehydrogenase （LDH） were increased significantly in HHcy group while folate and vitamin B₁₂ decreased serum CK-MB, CK and HBDH levels compared with HHcy group. The results of RT-PCR and immunohistochemical assay exposed an up-expressed P53 mRNA and protein in HHcy group. The changes of P53 mRNA and serum CK levels had positive correlation （r＝0.706 1, P<0.01）. Conclusions Hyperhomocysteinemia could result in the changes of myocardial enzyme spectrum, the homocysteine-induced oxidative stress might be its major pathogenic mechanism. The up-expressed P53 might also be involved in its pathogenesis. Replenishment of folate and vitamin B₁₂ could significantly antagonize the detrimental effects of exogenous Hcy.