1. Previous reports showed that the A1 allele of Taq1 A dopamine D2 receptor polymorphism was associated with lowered density and diminished function of dopamine D2 receptor. In this study, association between Taq1 A dopamine D2 receptor polymorphism and psychopathology of schizophrenia was investigated. 2. The subjects were 61 acutely exacerbated schizophrenic patients who were all Japanese descent and had received no medication for at least one month before this study. Pretreatment psychotic symptoms were assessed by the Brief Psychiatric Rating Scale (BPRS). The Taq1 A genotypes, the A1 and A2 alleles, were determined by polymerase chain reaction method. 3. The patients were divided into three genotype groups; i.e., the patients with A1/A1 allele (n=6), those with A1/A2 allele (n=32) and those with A2/A2 allele (n=23). 4. There was no significant difference in total BPRS, subgrouped symptoms (positive, negative, anxiety-depression, excitement and cognitive symptoms) or any scores of BPRS items among the three Taq1 A genotype groups. 5. The present study suggests that Taq1 A dopamine D2 receptor polymorphism does not play an important role in psychopathological symptoms of schizophrenia.