Parietaria judaica L. (Spreading pellitory) is a herbaceous plant that grows wildly in the urban areas in Turkey. Leaves of P. judaica were tested as a possible biomonitor of heavy metal pollution in Istanbul. Fifty three sites (urban, urban park, roadside, coast, suburban and rural) in and around Istanbul were investigated. Concentrations of Pb, Cd, Cu and Zn were determined in unwashed and washed leaves and soils collected from a wide range of sites with different degrees of metal pollution. Differences between the unwashed and washed samples varied according to the metal pollutant levels. The concentrations of heavy metals in the leaves of P. judaica increased along with the urbanization of the sites. Significant correlations were obtained between the heavy metal concentrations in surface soil and washed leaf samples. P. judaica was found to be a useful biomonitor of the investigated heavy metals.