OBJECTIVES: This study aimed to test the possible association between Glutathione S-Transferase M1 gene (GSTM1) variants and schizophrenia. METHODS: One hundred and eleven inpatients with schizophrenia and 130 healthy controls were recruited. Genotyping was performed by polymerase chain reaction-based method. RESULTS: The GSTM1 null genotype was significantly more frequent in patients with schizophrenia than in controls (p=0.014, odd ratio=1.93, 95% confidence interval=1.115-3.351), while GSTM1 genotype variants were not associated with either tardive dyskinesia (TD) or total Abnormal Involuntary Movement Scale (AIMS) scores. CONCLUSION: The present study suggests that the GSTM1 polymorphism may confer susceptibility to the development of schizophrenia but not to TD, at least in Korean population.