A method has been developed to analyze simultaneously 11 air polluting aromatic hydrocarbons. The samples were taken from a characteristic urban area of Budapest. Three of the compounds (3,4-benzpyrene, 1,2-benzanthracene and anthracene) could be detected in every sample. The rest occurred in the samples with a frequency between 89.5 and 20 per cent. On average 47 per cent of the total hydrocarbons detected in the samples were carcinogenic. The correlation between the various hydrocarbons and 3,4-benzpyrene is weak with the exception of pyrene.