The purpose of the present paper was to investigate the interleukin (IL)-4 promoter gene -590 and receptor alpha (Ralpha) gene 1902 polymorphism in Korean schizophrenic patients. A total of 222 Korean patients diagnosed with schizophrenia according to Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) and 165 normal healthy controls participated in the present study. The DNA was extracted from whole blood using proteinase K, and the IL-4 promoter and receptor gene were amplified by polymerase chain reaction. The genotype was determined using single-strand conformation polymorphism (SSCP) analysis. The distribution of the alleles and genotypes in patients with schizophrenia was not significantly different from those of controls. In conclusion, these results suggest that the polymorphisms in IL-4 promoter gene -590 and IL-4 Ralpha gene 1902 are not involved in the pathophysiology of schizophrenia in the Korean population.