It has been suggested by Arinami et al. (1994) that there is a positive relationship between schizophrenia and the Cys311 polymorphism of the Dopamine receptor D2 (DRD2) gene. However, some recent reports do not support this relationship. The differing results could be due to two causes, [1] There may be a regional difference in the proportion of schizophrenia due to the Cys311 or [2] the control groups in the recent studies might have included young schizophrenics. Accordingly, an analysis of the age of schizophrenic patients in the Fukuoka region was undertaken. The Cys311 allele frequencies for the control group was 0.040 and for the schizophrenic group was 0.057, which were not statistically different. Although this data did not corroborate the above mentioned positive relationship, it was found that the allele frequency was higher statistically than in any previous report for both the schizophrenic and control groups. These findings indicate that the frequency of the Cys311 is biased geographically and that this must considered when investigating the occurrences of genetic variants and diseases.