The ubiquity of polynuclear aromatic hydrocarbons (PAHs) in sewage sludges is now well documented. Since PAHs exhibit carcinogenic/mutagenic behaviour concern has been expressed over their fate following sludge application to agricultural soils. This paper presents a resume of the behaviour of sludge applied PAHs in soils and their propensity to transfer from the soil into plant tissues. This information is used to assess the environmental significance of PAHs in sludge amended soils. Sludge PAH inputs to the U.K. environment are compared with other known sources, such as waste disposal and atmospheric deposition and the possible impact of sludge application on human exposure is considered. It is concluded that at present there is no necessity to specifically regulate PAH inputs to agricultural soils in sewage sludge.