The aim of this selective review is to critically discuss the current evidence for a potential link between cholesterol, essential fatty acids, depression, suicide, impulsivity, & aggression. Preclinical data support the hypothesis that cholesterol reduction may contribute to the serotonergic abnormalities that have been postulated in suicidal subjects. Currently, we do not have sufficient evidence that cholesterol-lowering therapies increase the risk of depression & suicide. Increasing the dietary intake of omega-3 fatty acids may increase central serotonergic activity & reduce impulsive & aggressive behaviours. (66 refs)