Human exposure to environmental pollution is of great interest nowadays. Many substances present in the environment are considered as carcinogenic to humans. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental carcinogens. In this paper, PAHs are described: their physicochemical properties, natural and anthropogenic sources, environmental, dietary and occupational exposure and impact on human health. Metabolical carcinogenic activation of PAHs and the role of metabolism products as biomarkers of PAH exposure have been discussed.