['Matrix metalloproteinases (MMPs) play an important role in modeling and remodeling the extracellular matrix in leiomyomas. Hence, we investigated whether associations exist between leiomyomas and promoter polymorphisms in the MMP-1 and MMP-9 genes in a Japanese population.', 'We compared the distribution of polymorphisms in the promoter regions of MMP-1 (-1607 1G/2G) and MMP-9 (-1562 C/T) in 267 leiomyoma patients and 184 control patients using polymerase chain reaction-fragment-length polymorphism (PCR-RFLP) analysis.', 'The allele frequencies of the MMP-1 -1607 2G and MMP-9 -1562 T polymorphisms were 74.6% and 18.6% in leiomyoma patients, and 71.3% and 18.6% in control patients, respectively. No significant differences in allele frequencies or genotype distributions were found between leiomyoma and control patients. Moreover, no associations were found between MMP-1 and MMP-9 genotypes and leiomyoma size or a family history of the condition.'] Are matrix metalloproteinase-1 and -9 promoter polymorphisms associated with an increased risk of uterine leiomyomas in a Japanese population?