Matrix metalloproteinases (MMPs) are the enzymes which are directly involved in metastasis. Under physiological conditions MMPs are involved in such processes as embryogenesis, angiogenesis, cyclic changes in endometrium, wound healing and platelet aggregation. There is evidence that MMPs activity changes in many pathological conditions, including tumor disease, inflammatory and the degenera- tive diseases of nervous system. In cancer MMPs regulate growth and cancer-cell proliferation, metastasis, angiogenesis and the immune response to cancer. Gelatinase A (MMP-2) and gelatinase B (MMP-9) play an important role in cancer, because of their ability to degrade type IV collagen. The collagen type IV is the major component of basement membrane (BM). Loss of the continuity in BM structure determines the beginning of the cancer cell migration from primary tumor and creation of remote metastasis.