The A₁ allele of the D₂ dopamine receptor (DRD2) gene has been associated with alcohol dependence. However, the expression of this allele risk on the severity of drinking behavior in patients with alcohol dependence has not been systematically explored. The present study examines the association between DRD2 A₁⁺ (A₁/A₁ and A₁/A₂ genotypes) and A₁- (A₂/A₂ genotype) allele status and key drinking parameters in alcohol-dependent patients. A sample of Caucasian adults was recruited from an alcohol detoxification unit. A clinical interview and the Alcohol Dependence Scale (ADS) questionnaire provided data on consumption, dependence, chronology of drinking and prior detoxification. A₁⁺ allele compared to A₁- allele patients consumed higher quantities of alcohol, commenced problem drinking at an earlier age, experienced a shorter latency between first introduction to alcohol to the onset of problem drinking and had higher ADS scores. Moreover, A₁⁺ allele patients had more detoxification attempts than their A₁- allele counterparts. In sum, alcohol-dependent patients with the DRD2 A₁ allele compared to patients without this allele are characterized by greater severity of their disorder across a range of problem drinking indices. The implications of these findings are discussed.