DIAZEPAM-BINDING inhibitor (DBI) and its processing products, including the octadecaneuropeptide (ODN), are polypeptides called endozepines which have multiple biological effects, including regulation of mitochondrial steroidogenesis and modulation of GABA-gated chloride channels. Concentrations of ODN-like immunoreactivity (ODN-Li) were measured by radioimmunoassay in the frontal cortex of nine drug-free suicides and nine drug-free sudden-death victims. The level of ODN-Li was higher in the right than in the left frontal cortex, in both suicide (p< 0.05) and control (p< 0.02) subjects. No significant differences were found between suicides and controls either in the right and left cortex, or when considering the gender and the post-mortem diagnosis of depression.