Recent reports of a genetic association between restriction fragment length polymorphisms at the D2 dopamine receptor locus (DRD2) on chromosome 11q and alcoholism have suggested involvement of the D2 receptor protein in the aetiology of alcoholism, smoking and possibly other disorders. These allelic association findings have been criticized on the basis of the possible confounding of ethnic with disease differences, between allele frequencies of subjects and controls, and the fact that some of the control groups were not screened to exclude alcoholism or heavy drinking. We have observed the frequency of the A1 and A2 alleles in a population of 307 Caucasian British individuals screened for alcohol consumption of less than the UK Royal College of Psychiatrists' recommended sensible drinking limits for males and females and who also failed to qualify for a diagnosis of alcoholism according to the Research Diagnostic Criteria (RDC). The frequency of the A1 allele was found to be 0.20, which is slightly higher than most of the other screened Caucasian control groups from Europe and the United States. The allele and genotype frequencies in our sample are a resource for comparison with samples of alcoholics from the United Kingdom which have been selected on the basis of British ancestry and for residence in London. When we combined our new control data with that of the previous Caucasian control samples we found a significantly higher frequency of A1A1 homozygotes among the unscreened than the screened controls, suggesting that the DRD2 locus may be involved in drinking variation among the general population.