Three commonly used medicinal plants, e.g., Adhatoda vasica, Cassia fistula, and Withania somnifera grown in two contrasting environmental conditions, namely from copper mining site and from control site corresponding to soil not contaminated with Cu, to understand correlations between high Cu bioaccumulation in medicinal plants on their antioxidant activities. Concentrations of some essential metals, e.g., Cr, Mn, Fe, Cu, Zn, and Se in the leaves of these plants were measured by instrumental neutron activation analysis. The Cu levels in the samples from mining site were in the range of 32.6 to 57.2 mg/kg, which were 5–7 folds higher than the control samples, while Cr levels were about 2-folds higher in the mining site. Speciation studies of Cr revealed negligible content of toxic hexavalent Cr. Antioxidant assay of these plants from both the sampling sites, measured as total phenolic content, total flavonoid content, 2,2′-diphenyl-1- picrylhydrazyl, free radical scavenging ability, and chelating ability with ferrous ions exhibited maximum activity for A. vasica, while that of W. somnifera was minimum. However, the variations in the antioxidant activities for each medicinal plant species from mining site and control site did not reveal significant differences.