Tumor invasion, metastasis, and angiogenesis require controlled degradation of extracellular matrix, and increased expression of matrix metalloproteinases (MMPs) is associated with tumor invasion and metastasis of malignant tumors with different histogenetic origin, therefore several anti-MMP-targeted drugs are already under evaluation.MMPs and their natural tissue inhibitors (TIMPs) are also under consideration as prognostic factors in various malignancies.The goal of this study was to compare tumor expression and plasma levels of various MMPs and TIMPs in gastric and colorectal cancer in order to reveal most promising biological markers for these malignancies.