Relapse is the reinstatement of drug-seeking and drug-taking behaviors following a period of abstinence.It is one of the main characteristics of drug addiction and is also the major problem requiring immediate action for the treatment of drug addiction.In this review,in order to offer new ideas to eventually treat drug addiction,efforts are made to describe the establishment of two animal models of relapse-the drug self-administration (SA) and extinctionreinstatement procedure,and the drug-conditioned place preference(CPP) and extinction-reactivation procedure.Then attention is given to assess the criterion validity of the animal models of relapse and to explore the neurobiological mechanisms involved in relapse.