Objective:To explore the Predictor of cerebrospinal fluid monoamine metabolites in depressed inpatients with suicidal Bebaviors. Methods:Twenty-four patients with major depression and 25 controls were enrolled in the study. The CSF concentrations of 5-hydroxyindoleacetic acid(5-HIAA),norepinephrine(NE) metabolites 3-methoxy-4-hydroxyphenylglycol(MHPG) and dopamine(DA) metabolites homovanillic acid(HVA) were measured by high-pressure liquid chromatography. Twenty-four depressed patients were followed up in 5 years. The relationship between CSF monoamine metabolites and present suicidal behaviours(suicidal group and non-suicidal group) or suicidal behaviours followed up(suicidal group and non-suicidal group). Results:CSF 5-HIAA levels in suicidal group this time were significantly lower than those in control group. CSF MHPG levels in non-suicidal group this time were significantly lower than those in control group. CSF HVA levels in suicidal group this time were significantly lower than those in control group. CSF HVA levels in suicidal group this time were significantly lower than those in non-suicidal group this time. CSF 5-HIAA levels in suicidal group followed up were significantly lower than those in control group. Conclusion:It is suggested that 5-HIAA is associated with suicidal bebaviors. In depressed patients,5-HIAA perhaps can predict the suicidal behaviors.