© 2017 Begell House, Inc.The development of hepatocellular carcinoma (HCC) is a multistep process. In HCC, progressive and morphologically distinct preneoplastic lesions/alterations associated with chronic liver injury, inflammation, hepatocellular degeneration/regeneration, necrosis, and small-cell dysplasia can be observed. The incidence of HCC exhibits regional and ethnic differences. Several cytotoxic and DNA-damaging chemicals are suggested to be the underlying causes of HCC—for example, acrylamide, perfluorooctanoic acid (PFOA), polychlorinated biphenyls (PCBs), benzo(a)pyrene (BaP), perfluorinated chemicals (PFCs), vinyl chloride monomer (VCM), and dietary contaminants (aflatoxins, ochratoxins). Also suggested are substances of abuse (alcohol) and biological agents, such as hepatitis B and C and human immunodeficiency virus 1 (HIV-1). These can act through genetic and/or epigenetic mechanisms. This review will shortly address the genetic and epigenetic mechanisms of HCC and focus on cytotoxic and DNA-damaging chemicals and biological agents, exposure to which are suggested to lead to HCC initiation, promotion, and/or progression.