Substance use disorder" (SUD) is a common, chronic, remitting/relapsing group of psychiatric disorders having devastating effect not only on the individual but also impose socio-economic burden on their families and the society at large. They are often accompanied with numerous maladaptive behaviors and a persistent and compulsive, uncontrolled use of substance. Interestingly, they have moderate to high heritability and seem to be modulated by both genes and environment. Recent researches suggest that interactions of environmental and genetic factors designate the significance of epigenetic mechanisms, which have been found to occur in SUDs. This review makes an attempt to provide an overview regarding the various types of epigenetic modifications and their application in relation to SUDs.