Metabolic syndrome (MetS) is a collection of abnormal clinical and metabolic findings that are predictive of cardiovascular disease. The prevalence (approximately 30–40%) of MetS in patients with schizophrenia is higher than that in the general population, which is one of the reasons why patients with schizophrenia have a reduced life expectancy of 10 to 20 years compared to the general population. Many factors, including low exercise, smoking, unhealthy food, decreased medical service utilization, and treatments with antipsychotics (esp. olanzapine and clozapine), affect the development of MetS in schizophrenia patients. MetS in patients with schizophrenia may begin prior to antipsychotics and occur more often with the treatment of antipsychotics. Therefore, patients with schizophrenia, who are taking antipsychotics, should receive regular monitoring and adequate treatment of MetS.