Oxidative stress is considered a possible molecular mechanism involved in Lead (Pb) toxicity. Considering the vulnerability of the developing heart, liver and brain to Pb toxicity, this study was carried out to investigate the free radical scavenging activity of β – Sitosterol from methanol extract of Dodonoea viscosa linn leaf on Pb exposure on the heart, liver and regions of the brain. Adult male albino rats Wister strain were exposed to 200ppm of Pb, as Pb acetate in their drinking. The activities of antioxidant enzymes such as superoxide dismutase (SOD), Glutathione peroxidase (GPx) and Catalase (CAT) were determined in the heart and liver of male adult rats. Superoxide dismutase (SOD), gluthione peroxidase (GPx) and Glutathione reductase (GRed) were also determined in the brain of rats. In addition levels of non-enzymatic antioxidants namely vitamin E, vitamin C from plasma along with total reduced glutathione from liver and heart were also determined. In the Pb-exposed rats, the diminished activity of super oxide dismutase, Glutathione reductase and glutathione peroxidase in the brain of plant extract treated rats was significantly enhanced. The diminished activity of SOD, CAT, GPx in the heart and liver was increased. The decreased activity of vitamin E and vitamin C was normalized in the plasma of plant treated. There was a significant effect of the plant extract on the enzyme activity and the three regions of the brain evaluated in pb exposed rated. Based on the present results, it seems that oxidative stress due to decreased antioxidant function is normalized in methanol extract of Dodonoea viscosa linn solution treated rats. Toxicity in the organs tested and neurotoxicity in the brain is due to Pb exposure. And Spectral analysis of the methanol extract of Dodoneoa viscoasa lin was carried out.