The effects of heavy metals on the growth, development and accumulation of active constituents of silybum marinum were studied at three different areas, situated at a distance of 3 and 4 km from the main polluted area. The concentration of Cd, Cr, Pb, Cu, Mn, Zn and Fe was studied in soil as well as in the plants collected. The plant parts including roots, stems, leaves, seeds, oil and silymarin extracted from the seed were evaluated. Oil obtained from the seed was not contaminated with heavy metals. It was observed that heavy metals in soil and air pollution reduced the contents of cellular and a cellular constituents of silybum marinum. This showed that silybum marinum is suitable for the control of environmental pollutants, how ever, for pharmaceutical utilization; bit should be collected from areas not contained with heavy metals.