OBJECTIVE: There are several lines of evidence suggesting that matrix metalloproteinases (MMPs), particularly MMP-9, are involved in the pathogenesis of intracranial aneurysms. Some studies have demonstrated that genetic variants in the promoter region of the MMP-9 gene are associated with aneurysms. We performed a case-control study to investigate whether single-nucleotide polymorphisms (SNPs) within the coding region of the MMP-9 gene might affect the development of intracranial aneurysms. METHODS: All 13 exons and the 3′ untranslated region of the MMP-9 gene were analyzed by direct sequencing in a study group that comprised 40 Caucasian patients with at least one intracranial aneurysm and 44 Caucasian controls. Genotypes were determined, and those that were in Hardy-Weinberg disequilibrium were analyzed in another sample of 40 cases and 40 controls. Differences among the genotype frequencies of the identified polymorphisms were investigated. RESULTS: Seven SNPs were identified in the coding region, two were identified in the adjacent intronic sequences, and two were identified in the 3′ untranslated region. Genotype frequencies of four SNPs were demonstrated to be in Hardy-Weinberg disequilibrium in both analyzed study samples. Therefore, an accurate estimation of haplotype frequencies was not possible. No difference in genotype frequencies between cases and controls was detected at any of the 11 SNPs. CONCLUSION: SNPs of the coding region and the 3′ untranslated region of the MMP-9 gene are not associated with intracranial aneurysms in Caucasians.