Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between MTHFR polymorphism and psychiatric disorders susceptibility by using random effect models.<h4>Results</h4>We found that MTHFR C677T polymorphism is significantly related to schizophrenia and major depression in the overall population. Here, MTHFR is linked to schizophrenia.