Necrotic lesions were observed on the leaves of trees and herbaceous species in the vicinity of a copper refinery. Analysis of leaf samples revealed the presence of excessive concentrations of selenium and copper. The maximum levels, on a dry weight basis, were 550 μg/g Se and 340 μg/g Cu in the leaves of white poplar. Silver maple leaves from a nearby site contained 141 μg/g Se compared with 2 μg/g at an urban control site. Visual damage could be replicated by applying selenium dioxide to the leaf surface. These values are greatly in excess of selenium concentrations measured in vegetation in other industrial situations.