The purpose of this study was to investigate the influence of air pollution using epiphytic lichens on forest trees around Ulsan and Onsan industrial complex from April to June, 1997. The distribution of lichens was investigated at 58 sampled sites. In this study, 16 kinds of epiphytic lichens were recorded, of them, Leprazria sp. having a tolerance to air pollution showed the highest frequency as 30.85%, and in order of Lecanora strobilina(26.18%) and Parmelia austrosinensis(13.42%) unknown to tolerance of air pollution. The number of lichens was gradually decreased around industrial complex, where so called $quot;lichen desert$quot; was detected. As being distant from the industrial complex, the mean degrees of cover were increased. The degrees of cover in the investigated sites ranged from I to V. According to SO₂ concentration limiting lichen`s growth, the pattern of distribution of Cladonia sp., Dirinaria applanata, Parmelia austrosinensis, Lepraia sp. and Lecanora strabilina were dissimilar by sensitivity to air pollution Especially Lepraria sp. and Lecanora strabilina were widely distributed to degree of cover from I to V, and as the both had a similar distribution pattern, it could be inferred that Lecanora strobilina had also a tolerance to air pollution. The IAP values ranging from 0 to 64.3 were arranged into six groups and the investigated area was delineated into six IAP zones to represent degree of air environment. It was a high IAP value as being distant from industrial complex. The mare IAP increased, the more number of kinds of lichens increased. It was confirmed that the number of species, coverage and IAP value of epiphytic lichens showed a tendency to decrease of urban area and industrial complex.