The Micronucleus (MN) test is done to assess the genotoxic effects of the environment to the cell. It consists in identifying an error in the cell division where there is separation of chromosomes from the cell nucleus, thus forming a small fragment called a micronucleus. This may arise as a result of exposure factors of the body such as smoking, index, physical trauma, a potential risk for cancer development. There are several methodologies to obtain MN at laboratory level, which can be analyzed in cells of the oral mucosa, blood cells, defense cells such as lymphocytes. In addition, the test has a high cost-benefit, since it has low values and requirements less the examiner's expertise when compared to other methods. It is believed that the test can be used to identify possible carcinogenic risks arising from tobacco, ethanol, pesticides, radiotherapy, environmental and physiological factors such as aging, and can be used as a prognosis for several therapies.