Polycyclic aromatic hydrocarbons (PAH) are environmental contaminants produced in particular in combustion processes. As a consequence of their genotoxicity and ubiquity, they are the subject of an important research activity. After a presentation of the chemical structures and of the main physico-chemical and biological properties of these compounds, the current knowledge regarding their presence in the environment is summarized. The geochemical criteria of the different origins, pyrolytic, diagenetic and petroleum of PAH are presented. The respective contributions of their various emission sources are discussed, as well as the transfer and diffusion in the environ ment, the modifications undergone and the ultimate fate of these compounds. The qualitative and quantitative distribution of combustion PAH in soils in different environmental situations is presented.