Background: There has been a growing interest in the effect that comorbid mental and somatic disorders may have on each other. Metabolic syndrome is an important risk factor for the development of diabetes mellitus, cardiovascular disease and premature mortality. Objectives: To examine the association between various mental disorders (schizophrenia, schizoaffective disorder, bipolar disorder, depression, posttraumatic stress disorder and other mental disorders) and metabolic syndrome and discuss the possible pathophysiologic mechanisms that may link specific mental disorders and metabolic syndrome. Method: A MEDLINE search, citing articles from 1966 onward, supplemented by a review of bibliographies, was conducted to identify relevant studies. Criteria used to identify studies included (1) English language, (2) published studies with original data in peer-reviewed journals. Results: Clinical investigation of the metabolic syndrome in patients with mental disorders, except schizophrenia, has been surprisingly scarce. Metabolic syndrome was reported in 19-63% of schizophrenic patients, in 42.4% of patients with schizo-affective disorder, in 24.6-50% of bipolar patients, in 12-36% of the patients with recurrent depression and in 31.9-35% of patients with combat posttraumatic stress disorder. Conclusion: Metabolic syndrome can contribute to significant morbidity and premature mortality and should be accounted for in the treatment of mental disorders. No definite or reliable insight into the pathophysiological link between metabolic syndrome and mental disorders is available.