Abstract: Objective To study the association between Matrix Metalloproteinase-2 serum level, promoter region polymorphism(-735C/T), and the risk of hemorrhagic transformation in acute cerebral infarction patients. Methods The polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) method was used to detect MMP-2 gene promoter region -735C/T site polymorphism in 581 cases of acute cerebral infarction patients. According to the genotypes, all specimens were divided into CC group and CT+TT group, and then the general and acute cerebral infarction hemorrhagic transformation was compared. Results There were no statistically significant difference in the age, sex, Systolic and diastolic blood pressure at admission, smoking and drinking history, blood glucose, triglyceride, low density lipoprotein cholesterol, NIHSS scores, anti-platelet therapy between the two groups(P>0.05). There were 52 cases of hemorrhagic transformation in CC group, accounting for 16.35%, while 26 cases of hemorrhagic transformation in CT+TT group, accounting for 9.89%, the difference between the two groups was statistically significant(P=0.023), and it showed that the hemorrhagic transformation rate of CC group was significantly higher than that in CT+TT group. In the CC group serum level of MMP-2 was also significantly higher than that in the CT+TT group(P=0.017). Conclusion The locus of MMP-2(-735C/T) polymorphism may be associated with the risk of hemorrhagic transformation in patients with acute cerebral infarction. CC genotype may be the susceptible genotype of hemorrhagic transformation in acute cerebral infarction patients, while the CT+TT genotype may be protective genotypes; the C allele may be a susceptible allelic gene, and the T allele may be a protective allelic gene.