Because of the necessity for balance between MMPs and TIMPs, it is not surprising that a differential expression of MMPs and TIMPs is associated with the pathophysiology of endomiolysis and the imbalance between the secretion of MMP-9 and its natural inhibitor TIMP-1 in the culture milleu of endometriosis tissue probably reflects the increased ability of this tissue in vivo to cleave the extracellular matrix, thereby facilitating the ectopic implantation of endometrial growth. Here, MMP9 is linked to endometriosis.