Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that degrade various proteins in the extracellular matrix (ECM). They are classified based on their substrates and structural domains into collagenases, gelatinases, stromelysins, matrilysins, membrane-type (MT)-MMPs, and others. MMPs are produced by multiple cells and tissues, including fibroblasts, vascular smooth muscle (VSM), and leukocytes, and are regulated at the mRNA level and by activation of their latent zymogen form. MMPs play crucial roles in tissue remodeling during physiological processes such as angiogenesis, embryogenesis, and wound repair, as well as in pathological conditions like myocardial infarction, fibrotic disorders, osteoarthritis, and cancer. They can be regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio determines the extent of ECM protein degradation. MMPs have been proposed as biomarkers for various pathological conditions and are being explored as therapeutic targets in cardiovascular and musculoskeletal disorders, as well as cancer. The chapter provides an overview of the biochemical and biological properties of MMPs, including their structure, tissue distribution, protein substrates, activation, and specific classes of MMPs. It also discusses their roles in cardiovascular diseases, inflammatory and musculoskeletal disorders, and cancer.Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that degrade various proteins in the extracellular matrix (ECM). They are classified based on their substrates and structural domains into collagenases, gelatinases, stromelysins, matrilysins, membrane-type (MT)-MMPs, and others. MMPs are produced by multiple cells and tissues, including fibroblasts, vascular smooth muscle (VSM), and leukocytes, and are regulated at the mRNA level and by activation of their latent zymogen form. MMPs play crucial roles in tissue remodeling during physiological processes such as angiogenesis, embryogenesis, and wound repair, as well as in pathological conditions like myocardial infarction, fibrotic disorders, osteoarthritis, and cancer. They can be regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio determines the extent of ECM protein degradation. MMPs have been proposed as biomarkers for various pathological conditions and are being explored as therapeutic targets in cardiovascular and musculoskeletal disorders, as well as cancer. The chapter provides an overview of the biochemical and biological properties of MMPs, including their structure, tissue distribution, protein substrates, activation, and specific classes of MMPs. It also discusses their roles in cardiovascular diseases, inflammatory and musculoskeletal disorders, and cancer.