This chapter discusses the mechanisms of carcinogenicity for metals and their compounds, focusing on metals classified as carcinogenic to humans or considered to be carcinogenic to humans. The physicochemical properties of these metals, such as oxidation state, charge, and size, govern their uptake, distribution, and binding within cells. Interactions with proteins, particularly zinc finger structures, are more significant for metal carcinogenicity than DNA binding. The genotoxicity of metals is primarily indirect, involving three main mechanisms: interference with cellular redox regulation and oxidative stress, inhibition of DNA repair systems, and deregulation of cell proliferation. Specific metal compounds exhibit unique mechanisms, such as cadmium's disruption of cell-cell adhesion, trivalent chromium's direct DNA binding, and vanadate's interaction with phosphate binding sites of protein phosphatases. The chapter also provides an overview of the classification of these metals by scientific and regulatory bodies, highlighting the complexity and diversity of metal interactions with biological systems.This chapter discusses the mechanisms of carcinogenicity for metals and their compounds, focusing on metals classified as carcinogenic to humans or considered to be carcinogenic to humans. The physicochemical properties of these metals, such as oxidation state, charge, and size, govern their uptake, distribution, and binding within cells. Interactions with proteins, particularly zinc finger structures, are more significant for metal carcinogenicity than DNA binding. The genotoxicity of metals is primarily indirect, involving three main mechanisms: interference with cellular redox regulation and oxidative stress, inhibition of DNA repair systems, and deregulation of cell proliferation. Specific metal compounds exhibit unique mechanisms, such as cadmium's disruption of cell-cell adhesion, trivalent chromium's direct DNA binding, and vanadate's interaction with phosphate binding sites of protein phosphatases. The chapter also provides an overview of the classification of these metals by scientific and regulatory bodies, highlighting the complexity and diversity of metal interactions with biological systems.