Two groups of cheese were analysed for their polycyclic aromatic hydrocarbon (PAH) content. The first group was composed of 24 highland Swiss L`Etivaz cheeses manufactured using an open fire with logs, and 25 Swiss Gruyere cheeses manufactured in a steam heated vat as a reference. In the highland cheese, anthracene was often present, fluoranthene, fluorene and naphthalene were found occasionally. All these compounds are related to the processing technology. Phenanthrene and pyrene were found in a higher concentration in the highland cheeses than in the reference cheeses, thus indicating that the latter compounds originated from both the environment and the smoke of the fire. In conclusion, these various components may be considered as labelling substances for highland cheese with a Protected Designation of Origin (PDO). The second group was comprised of 18 Swiss or foreign cheeses, 9 with and 9 without smoke flavour as reference. In most cheeses treated with warm smoke, the same PAH occurred in a much higher concentration than in the highland cheeses previously considered. Moreover, several other PAH were found such as benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene. Benzo(a)anthracene is present in trace amonts in all cheeses analysed and seems to be a pollutant that is not related to the smoking procedure. Liquid smokes (9 = 3) do not contain any PAH but are nevertheless highly efficient flavouring preparations. Their use may consequently he recommended as a valuable alternative procedure resulting in lower risks to human health in comparison with the use of warm smoke