Metabolic syndrome, including diabetes, increased fasting plasma glucose, abdominal obesity, high cholesterol and high blood pressure, is a cluster of risk factors for cardiovascular diseases. Clozapine is one of the atypical antipsychotics which have negative effects on body weight, plasma lipid concentration and plasma glucose control, and may increase the risks of suffering from metabolic syndrome. The relationship between clozapine and metabolic syndrome is reviewed in this paper.