Soil as a major natural resource constitutes the biosphere. Human activities, including agricultural, industrial and mining activities led to soil degradation. In this regard, the presence of various inorganic and organic contaminants in soil is one of the challenges that mankind face. Among the non-biodegradable contaminants, heavy metals and their physiological effects on living organisms, human health threat, followed by their entry into the food chain even at low concentration are important. Of the major heavy metals, lead, zinc and cadmium can be pointed out. Agricultural soils health plays a key role in food and society health. One way to address the soil contamination is to reduce the availability of heavy metals for plant uptake. Organic materials through humification may stabilize the heavy metals on carboxyl groups of humic acids reducing the metal bioavailability in the root environment. Sources of organic matter amendments to soils are mainly manure, plant residues and different types of composts. In this work the effects of two organic amendments on lead, zinc and cadmium uptake of lettuce from a naturally and a hand-made contaminated soil were investigated. The naturally contaminated soil was sampled from 0-20 cm depth of Bama mine vicinity region, 20 km south west of Isfahan. A surface non contaminated soil sample was obtained from Chah Anari farm, Isfahan University of Technology. The artificially polluted soil was made of the later sample using lead, zinc and cadmium chloride salts. The experiment was carried out in Isfahan University of Technology trial greenhouse as a completely randomized factorial design with three replications. The treatments were; municipal solid waste compost and cow manure each at three levels (0, 0.5 and 1% as organic carbon), two cultivars of lettuce ( Conquistador and Grizzly ) and three soil samples (naturally and hand-made contaminated and a non contaminated soil). The results showed that the addition of municipal solid waste compost and cow manure increased the dry weight of both lettuce cultivars. The maximum dry weight yield of both lettuce cultivars obtained from non contaminated soil, while the artificially contaminated soil produced the minimum yield. The municipal solid waste compost treatment produced higher root dry weight yield in Conquistador in comparison with manure. The root dry weight decreased with increasing organic amendment levels. The municipal solid waste compost showed a higher lead and zinc content in lettuce shoots. Addition of organic amendments to the soils reduced the lead concentrations in shoots of both lettuce cultivars. Manure showed a higher Cd concentration in lettuce shoot over the compost. The organic amendments decreased the lead concentration in the roots of Conquistador , while decreasing zinc and cadmium in the roots of both cultivars. The peroxidase and catalase activities in shoots of both cultivars grown in non contaminated soil were lower than the contaminated soil. Addition of organic amendments to the soil decreased the peroxidase activity of lettuce shoots in both cultivars. Catalase activity in lettuce treated with manure was higher than the compost treatment. The amendments decreased catalase activity in shoots of Grizzly , but the decrease in Conquistador was not significant. Key words: Antioxidant enzymes, heavy metals, lettuce, manure and municipal solid waste compost