The object of this study was to examine the effects of air pollution on forest vegetation structure in the vinicity of Sasang industrial complex in Korea. Forest vegetation structure was investigated at 19 sample plots surrounding industrial complex and at one site away from industrial complex as a control. The results obtained were as follows; 1. For analysis of vegetation structure, upperstory of forests was mostly consisted of Pinus thunbergii, and partly of Alnus firma and Robinia pseudoacacia. In midstory, major components were Pinus thunbergii, Robinia pseudoacacia, Rhus trichocarpa, Rhus chinensis and Styrax japonica, In lower story, Pinus thunbergii was a minor component, while Robinia pseudoacacia, Quercus serrata, Rhus trichocarpa. and Rhododendron yedoense var. poukhanense which were known to be resistant to air pollution were found in large number. Especially, importance percentage of Robinia pseudoacacia was high, while that of Rhododendron mucronulatum was low in surrounding industrial complex. 2. For woody plants, number of species, species diversity and similarity index in industrial complex, were not significantly different from those in control plot. 3. For herbs, Oplismenus undulatifolius appeared in large number in most plots. The SDR₃ of Miscanthus sinensis, Calamagrostis arundinacea, Paederia scandens, Spodiopogon cotulifer and Carex humilis were high, but that of Aster scaber, Saussurea seoulensis, Solidago virgaaurea var. asiatica and Prunella vulgaris var. lilacina were low in the vicinity of industrial complex. 4. Number of herb species decreased to below 10 species at surrounding industrial complex as compared to 20 species in the control plot. In addition species diversity, and similarity index in the industrial complex were lower than those in control plot. It may be concluded that Pinus thunbergii forests in industrial complex consists of tree species resistant to air pollution, and that composition of woody vegetation in industrial complex was not much different from control plot, while composition of herbs was already quite different between the two plots. Forest vegetation structure, therefore, may change with time due to air pollution in the industrial complex.