Abstract The gene encoding d-amino acid oxidase (DAO), which acts as a receptor for the schizophrenia-associated neurotransmitter, N-methyl-D-aspartate (NMDA), is regarded as a potential candidate gene for schizophrenia. However, the potential association of the DAO gene with schizophrenia has been the subject of some debate. Here, we tested three single nucleotide polymorphisms (SNPs) of DAO in a group of Korean schizophrenia patients, and found no significant association in the overall study subjects. Interestingly, however, we found gender-specific differences in allele distributions, with SNP rs2070586 appearing to act as a risk allele in female schizophrenia patients, but as a protective allele in males. Our data support the hypothesis that DAO plays a role in schizophrenia, possibly in a gender-dependent manner.