This study aims to compare allele and genotype frequencies of a 30-bp variable number of tandem repeats (VNTR) polymorphism of the\u00a0DAT1\u00a0gene, located at intron 8, between adult crack cocaine users and nonaddicted individuals. Due to its involvement in drug addiction, this gene is a good candidate for molecular studies.\u00a0Methods:\u00a0A cross-sectional sample of 239 current adult crack abusers or dependents from in- and outpatient clinics and 211 control individuals was collected in Brazil. They were evaluated using ASRS, ASI-6, WAIS-III, and MINI assessments. DNA samples extracted from whole blood were genotyped for the intron 8 VNTR in\u00a0DAT1.\u00a0Results:\u00a0Logistic regression analysis was performed and controlled for gender, age, ethnicity, educational level, and comorbidities of clinical interest (generalized anxiety disorder, suicide risk, major depressive episode, and attention deficit\/hyperactivity disorder). This analysis showed that the 6R6R genotype was associated with crack cocaine addiction (OR = 1.844; CI = 1.101\u20133.089;\u00a0p\u00a0= 0.020).\u00a0Conclusions:\u00a0Our results are consistent with the role of\u00a0DAT1\u00a0in the neurobiology of drug addiction. Nevertheless, the study of other genes, environmental factors, and their interactions is also important to gain a broader understanding of this condition.<\/p>\n\n\n\n