Dopamine receptors have been implicated in the aetiology of schizophrenia and mode of action of antipsychotic drugs. A finding of increased homozygosity at the D3 receptor gene (BalI locus) has recently been reported. We have investigated the distribution of D3 receptor gene polymorphism (BalI) in 137 schizophrenic Chinese males and 125 healthy matched controls. The frequency of the rare allele was 0.30 and 0.31 in the patient and the control series. The distribution of genotypes in the patient series did not deviate significantly from Hardy-Weinberg equilibrium in the present series.