The main theme of my research is suicide prevention to which I have taken three approaches. The first is the study of molecular psychiatry in suicide completers. In this study, the object is to clarify the biological susceptibility of suicide. Association studies have mainly been performed between the polymorphisms of monoamine-related genes and suicide. The second approach is the clinical study of such psychotropic drugs as antidepressants and antipsychotics to scientifically verify their efficacy and safety. I am specifically interested in the validity of the study designs and assessment measures. The third approach is the clinical practice of mood disorders (depression). The case reports of mood disorders (depression) would be beneficial to prevent suicide. Mood disorders (depression) are representative of the mental disorders involved in more than 90% of suicides. I have been broadly applying basic science to clinical practices to obtain scientific evidence for suicide prevention.