The effect of four air pollutants (NO_X, NH₃, SO ₂, & O₃) upon epiphytic macrolichens in the urban environment was explored. Lichens were examined at seven urban and four non-urban (rural or suburban) sites in the greater Cincinnati metropolitan area. A total of 31 species of lichens were found, including 19 new county records for four southwestern counties in Ohio, and four new county records for Boone County, Kentucky. The abundance of each lichen taxon, estimated as percent cover, was compared against air pollution data using multiple linear regression and non-metric multidimensional scaling (NMS) ordination. Both techniques revealed that O₃, NO_X and NH₃ have a significant impact on lichens in the urban environment. Linear regression techniques did not reveal a significant impact from SO₂ on urban lichens, however NMS ordination suggested that the effect of SO₂ is simply overwhelmed by the effects of the other pollutants.