Chemical carcinogens are supposedly considered to be the key etiological factor of malignancy. The covalent or non-covalent bonds between these chemical and the DNA, RNA, and proteins of human tissue help in the initiation of carcinogenesis wherein, genetic mutation and alteration in the genome transcription supervenes. These carcinogens behave as initiators or promoters of cancer cell growth. Alkylation of DNA, RNA, or proteins and the formation of covalent bonds with them begins initially followed by the promoting effect. Numerous molecular and cellular events causing the transformation of normal cells into neoplastic cells occur in the process. It is assumed though that endogenous molecular pathways could instigate mutations in respective genes with the support of reactive oxygen species thus leading to DNA damage. Thus, this review deals with the basic mechanism and metabolism of chemical carcinogenesis.