Hepatitis C is highly prevalent among intravenous drug abusers, but to date research has not widely explicated behavioural risk factors regarding acquisition of infection. The A₁allele of the D₂ dopamine receptor (DRD2) gene is a hypothesized risk factor in the development of severe drug dependence and alcoholism. The present study compares the frequency of the A₁ allele of the DRD2 gene among 37 patients presenting to a hepatitis clinic for treatment of hepatitis C, 23 hepatitis C-negative drug-abusing patients maintained on methadone and 33 non-drug-abusing controls. The results indicated that hepatitis C-positive patients were significantly more likely to display the A₁ allele than hepatitis C-negative patients, who were in turn more likely to have the A₁ allele than controls. Furthermore, the hepatitis C subjects manifested more persistent drug-seeking behaviour than the other drug-abusing group. The implications of this finding in terms of drug-related reward are discussed. Future research should attempt to evaluate host risk factors, in order to enable more precisely targeted attempts at harm minimization.