Studies of the neurobiology of suicidal behavior have become an important and integral part of psychiatric research. Over the past several years, studies of the role of brain-derived neurotrophic factor (BDNF) in the pathophysiology of suicidality have attracted significant interest of researchers. Multiple lines of evidence including studies of levels of BDNF in blood cells and plasma of suicidal patients, postmortem brain studies in suicidal subjects with or without depression, and genetic association studies linking BDNF to suicide suggest that suicidal behavior may be associated with a decrease in BDNF functioning. Studies of the BDNF function are important for suicide research and prevention because of the multiple reasons including the following: (i) BDNF plays a role in the pathophysiology of depression, post-traumatic stress disorder, substance use disorders and other conditions associated with suicidal behavior. Treatment-induced enhancements of BDNF can facilitate neural integrity and recovery of function in psychiatric disorders, and consequently prevent suicidal behavior; (ii) abnormal BDNF function may be associated with elevated suicidality independently of psychiatric diagnoses. It is possible that treatment-induced improvement in the BDNF function prevents suicidal behavior independently of improvement in psychiatric disorders; (iii) BDNF may be a biological marker of suicidal behavior in certain patient populations. It is to be hoped that the studies of the neurobiology of suicidal behavior will lead to the development of new methods of suicide prevention.