Air pollution is among the major problems stemming from modern urban life. Millions of people worldwide die from air pollution every year. Especially heavy metals have great importance among these pollutants. Because heavy metals can stay in nature for a long time without deterioration, and their concentration in the environment is constantly increasing. They also tend to bioaccumulate. Many heavy metals arise from exhaust gases, car wheels, vehicles, and vehicle corrosion in cities. Determining heavy metal concentrations in plants is important both for determining the ability of plants to remove heavy metals from the air, and thus to be used as a means of increasing air quality, as well as for monitoring air quality. The purpose of this study is to determine the variation of different heavy metal concentrations, depending on the traffic density, in some landscape plants sampled from areas with different levels of traffic density. Our results show that heavy metal accumulation differs according to both plant species and traffic density. In traffic-dense areas we measured the greatest amounts of Cu, Ni, and Fe in Prunus cerasifera; of Ca, Mg, and Mn in Ailanthus altissima; of Cr and Zn in Elaeagnus angustifolia; and of Pb and Cd in Tilia tomentosa.