We report on sporadic cases that have the proposed diagnostic criteria for Cohen syndrome associated with metabolic syndrome. The patients, aged 14 and 16 years, had truncal obesity, mild mental retardation, hypotonia, narrow hands and feet, a high-arched palate, prominent upper central incisors, a high nasal bridge, and ocular abnormalities. Both had impaired glucose tolerance, with marked hyperinsulinemia exhibited by an oral glucose tolerance test. Moreover, they had the other metabolic syndrome features of hyperlipidemia and hypertension. We suggest that it is necessary to consider the possibility of metabolic syndrome in a case of Cohen syndrome.