Matrix metalloproteinases (MMPs) may contribute to the development of endometriosis. The aim of this study was to assess the effects of the polymorphisms in the promoters of MMP-7 (181A/G) and MMP-9 (1562C/T) on the risk of occurrence of endometriosis and adenomyosis. We genotyped 219 patients (143 women with endometriosis, 76 women with adenomyosis) and 160 control women in North China. There was a significant difference in frequency of the MMP-7 genotype between endometriosis and controls (P = 0.01) and also between adenomyosis and controls (P = 0.01). The frequency of the G allele in two groups of patients (7.3 and 7.9%) was significantly higher than in the controls (2.8%) (P = 0.01 and 0.01, respectively). Compared to the A/A genotype, the genotype with the -181G allele showed a significantly increased susceptibility to both diseases, with adjusted odds ratio of 2.62 [95% confidence interval (CI) = 1.17-5.87] for endometriosis and 3.14 (95% CI = 1.26-7.81) for adenomyosis. However, the overall genotype and allelotype distribution of the MMP-9 in the two case groups were not different from that of controls. We conclude that MMP-7-181A/G polymorphism has a potential to be a susceptibility factor for endometriosis and adenomyosis while MMP-9-1562C/T polymorphism may not provide a useful marker to predict susceptibility to endometriosis and adenomyosis, at least in women from North China.