Lysyl oxidases (LysOX; EC 1.4.3.13, protein-lysine 6-oxidases) are extracellular copper enzymes that catalyze the cross-linking of collagens or elastin in the extracellular matrix (ECM), thereby regulating the tensile strength of tissues. Recent implication of LysOX in cancer, wound healing, cell motility, chemotaxis, and differentiation reflects its remarkable functional diversity and also in the central nervous system pathologies. However, recent reports also demonstrated novel roles for LysOX, including the ability to regulate gene transcription, motility/migration, and cell adhesion. These diverse functions have led researchers to hypothesize that LysOX may have multiple roles affecting both extra- and intracellular cell function(s). Both down and up-regulation of LysOX in tumor tissues and cancer cell lines have been described, suggesting a dual role for LysOX as a tumor suppressor, as well as a metastasis promoter gene. In this review we explain in detail the role of lysyl oxidase in tumor progression and metastasis.