Today's psychotic patient is more and more at risk from metabolic syndrome. This syndrome, whose core criteria were standardised by expert consensus in 2004, represents a significant cause of increased morbidity and mortality in such a psychiatric population. The constellation of risk factors of metabolic syndrome associates central obesity with at least two of the following: hyperlipidaemia, hypercholesterolaemia, arterial hypertension or fasting hyperglycaemia. The reasons why psychotic patients are more at risk for these complications are still debated although one can reasonably suggest a multi-factorial aetiology. Among the causes which seem to contribute significantly and moreover which the clinician may be able to have a positive influence over are antipsychotic medication and patient lifestyle. Since the introduction of second-generation antipsychotics complications of the metabolic syndrome have increasingly drawn clinicians' attention. Based on current guidelines, we propose a classification of risk for metabolic syndrome according to specific medication: the high-risk group consists of clozapine and olanzapine, the medium-risk group of risperidone, quetiapine and amisulpiride, the low-risk group of aripiprazole and sertindole. The mechanisms through which antipsychotic medication induces metabolic-syndrome symptoms are now actively researched. A probable hypothesis implicates deregulation of energy homoeostasis in the central nervous system (essentially at the hypothalamic level). This deregulation would be exerted through specific neurotransmitter systems with which medication interferes. At the moment, most data support the relevance of interaction at the histaminergic and serotoninergic receptors. However, other hypotheses supported by recent research suggest a significant medication interaction at the peripheral level, such as the pancreas or adipose tissue. For the clinician the priority remains how to use today's knowledge to best prevent and treat metabolic syndrome in his or her patients. We propose a therapeutic attitude intervening at several levels with early detection of possible signs, judicious adaptation of antipsychotic medication, lifestyle intervention and, if necessary, specific treatment of metabolic syndrome symptoms.