This paper describes on the distribution of polynuclear aromatic hydrocarbons (PAHs) in various size of atmospheric particulate matter (A.P.M.). A.P.M. in Seoul city were collected on guartz fiber filter according to particle size using an Andersen high volume air sampler from Feb. 1983 to March 1984. And 7 PAHs [benzo(a)pyrene, benzo(k)fluoranthene, benzo(ghi)perylene, benzo(e) pyrene, perylene, chrysene, and pyrene] were analyzed by high performance liquid chromatography. The concentration of A.P.M. showed spring-winter maxima and summer-autumn minia. The A.P.M. was lowest in the concentration at the 1.1~3.3$mu extrm{m}$ particulates, and the concentration increased as the particle size increased or decreased. But the concentrations of PAHs increased with the decrease in the particle size, and were predominant in winter. The correlations among the PAHs were high. And there fore, benzo(a)pyrene concentration could be considered as the representive of PAHs.