Drug dependence has been a hot topic in neuroscience research due to its complicated pathogenesis. Recently, huge scientific efforts have been continuously put into understanding the association between drug dependence and polymorphism in ATP-binding cassette subfamily B member 1 transporter ( ABCB1 ) gene, especially a mutation in exon 26 at position 3435 (3435C>T). This article reviews the relationship between opioid dependence and analgesic tolerance and ABCB1 gene pol-ymorphism, which will shed light on the underlying mechanisms of drug dependence and optimal MMT programs for individuals.