Iraqi Center for Genetics and Cancer Research, University of Al-Mustansiriyah delivered a lecture on heavy elements, their toxicity and role in causing of cancer. The lecture, in which a number of researchers and specialists participated, reviewed the impact of heavy elements with high atomic mass on human health such as arsenic, cadmium, lead and mercury, which are characterized by being highly toxic substances and play a fundamental role in causing various tumors. The lecture highlighted mechanism of the effect of the heavy elements and their toxic action against human body which is through generating free radicals which known in their damage to the structure of healthy cells and DNA, interfere with the work of some important enzymes and how these elements reach the human body through cigarette smoke, paints, polluted water and underground water. The lecture also reviewed that these elements are found primarily in nature, where the continuous human activity leads to increase their concentration in water, air, food and soil besides the recent scientific studies approved the existence of a fundamental relationship between the increasing concentrations of these elements and the biological and genetic changes that affect the cellular to cause cancer.