In most parts of the world, tobacco is used for smoking, whereas, in India, tobacco is used for smoking as well as in diverse smokeless forms. Absorption of toxic and carcinogenic chemicals in tobacco and other ingredients added to various products are causally associated with several non-communicable diseases including cancer, especially oral cancer, which is the leading cancer among men and the third most common cancer among women in India. This article highlights the toxicity, mutagenecity and carcinogenic effects of hazardous chemicals present in smokeless tobacco products. This endeavor was based on the extensive review of literature from various sources. The SLT products have influence on cellular metabolism, ability to cause DNA damage, and cancer in experimental animals. It is, therefore, essential to consider the collective role of chemical constituents of SLT products in the causation of adverse effect on human health.