- This article describes the current scientific knowledge regarding pharmacogenetic predictors of treatment outcome for substance-dependent patients.- PubMed was searched for articles on pharmacogenetics and addiction. This search yielded 53 articles, of which 27 were selected.- The most promising pharmacogenetic findings are related to the treatment of alcohol dependence. Genetic variation in the micro-opioid receptor (OPRM1) and the serotonin transporter (5-HTTLPR) appear to be associated with treatment outcomes for naltrexone and ondansetron, respectively. - Genetic variation in CYP2D6 is related to efficacy of methadone treatment for opiate dependence. - Pharmacogenetics may help explain the great inter-individual variation in treatment response. In the future, treatment matching, based on genetic characteristics of individual patients, could lead to a 'personalized medicine' approach. Pharmacogenetic matching of naltrexone in alcohol-dependent carriers of the OPRM1 G-allele currently seems most promising.