The present study was carried out to examine the relationship of interleukin (IL)-10 gene polymorphism at position -819 for major depression and schizophrenia in the Korean population. DNA was extracted from 92 Korean patients with major depression, 141 Korean patients with schizophrenia, and 146 ethnically matched controls. DNA was amplified by a polymerase chain reaction-based method and digested by MaeIII, and the restriction fragment length polymorphism of two alleles, IL-10*C and IL-10*T, were assessed. There were no significant differences in genotype frequencies of IL-10*T/T, IL-10*T/C, and IL-10*C/C as well as allelic frequencies of IL-10*T and IL-10*C between patients with major depression and controls in the Korean population. Comparison of genotype and allelic frequencies of IL-10 gene between patients with schizophrenia and controls were also not significant. The present study suggests that IL-10 gene polymorphism at position -819 does not confer susceptibility to major depression and schizophrenia, at least in the Korean population. Further systematic studies including various clinical variables would be required.