Several studies suggest that the reduction of total cholesterol in blood by lipid-lowering agents is accompanied by a decrease in the incidence of coronary heart disease, but not in total mortality. Likewise, epidemiological studies show that low total cholesterol concentrations appear to be associated with an increased risk of death from suicide and injuries. There is little information with respect to acute suicidality and cholesterol in psychiatric inpatients; therefore the aim of the present study was to examine exactly this relation between plasma cholesterol and acute suicidality. The study comprised 45 acutely suicidal psychiatric inpatients, 95 nonsuicidal inpatients with affective disorder, and 20 healthy subjects. Psychopathological measures (Brief Psychiatric Rating Scale, Hamilton Depression Rating Scale, Beck's Suicide Intent Scale) were established in these patients as well as the plasma concentrations of cholesterol in patients and healthy subjects. The most important finding of this study is that the risk of acute suicidality decreases with increasing total cholesterol levels irrespective of age, gender, and nutritional status (i.e., body mass index). Comparison of total cholesterol levels between age- and sex-matched suicidal and nonsuicidal patients with affective disorder supports this observation: Despite the slightly higher body mass index, suicidal patients have significantly lower cholesterol levels than nonsuicidal patients. Our findings support the notion that acute suicidality is associated with low plasma cholesterol; this observation needs to be further studied in the context of a biological marker for suicide risk.