AIM:To examine the association between the single nucleotide polymorphisms (SNPs) of matrix metalloprotease-9 (MMP-9) gene and primary angle-closure glaucoma (PACG) in a Chinese Han population.METHODS: DNA samples were extracted from peripheral-blood mononuclear cells of 214 PACG patients and 224 healthy controls. Genotyping of rs3918249, rs3918254, rs17577 and rs3787268 in MMP-9 was performed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis and the direct sequencing technique. The association between these genetic polymorphisms and risk of PACG was estimated by χ² test.RESULTS: The distributions of rs3918249, rs3918254, rs17577 and rs3787268 genotypes among cases and healthy controls were compatible with that from Hardy-Weinberg equilibrium (HWE, P>0.05).The increased frequency of CC and CT genotypes of rs3918254 were observed in PACG patients compared to healthy controls [P=0.006, Pcorrected (Pcorr)=0.048]. The haplotype analysis showed that the CCGG haplotype was nominal associated with PACG (P=0.015), however, the significant was lost when the Bonferroni correction was used (Pcorr=0.105).CONCLUSION:Our results revealed that rs3918254 in MMP-9 may be a susceptible locus to PACG in China, people with the CC and CT genotypes of rs3918254 are more susceptible to PACG. The susceptibility to PACG in Chinese Han patients may be not influenced by SNPs rs3918249, rs3787268 and rs17577 in MMP-9.