Abstract In this investigation we focus on the concentration of elements in Polygonum aviculare as a bioindicator of urban pollution. This highly widespread species with a colonising ability to survive in wastelands where other species have vanished may provide important information to monitor environmental quality. Cd, Cu, Fe, Mn, Ni, Pb and Zn concentrations in P. aviculare and in the soil in which the plant grew were measured on 79 sites affected by various levels of pollution. P. aviculare showed greater accumulation of Cd, Cu, Fe, Ni, Pb and Zn in the Wroclaw metropolitan area mainly due to vehicular traffic. The heavy street traffic and industrial emissions involved the highest Cd, Cu, Pb and Zn concentrations in the shoots, while highway exhausts only led to the highest Ni and Fe concentrations in the shoots. Cd, Ni and Pb sequestration in roots probably enables P. aviculare to continue uninhibited growing, an important mechanism of metal tolerance. This species takes up and allocates essential micronutrients (Cu, Mn and Zn) in photosynthetic tissues.