Ketamine, a widely used anesthetic agent, is currently being investigated as a novel therapeutic for depression and suicidality. Ketamine has garnered substantial attention from researchers, clinicians, media outlets, and patients alike, but numerous questions remain. One of the compelling features of ketamine is the rapidity of its antidepressant effects, which peak just 24 h after infusion, setting it apart from other existing treatments. Ketamine's rapid time course has inspired research efforts to explore its potential as a life-saving therapy for patients at imminent risk of suicide. In this article, we review current evidence supporting the rapid effects of ketamine on suicidal ideation in the context of unipolar and bipolar depression. We then discuss several future directions that are necessary before ketamine can be considered a viable treatment option for suicidality in clinical settings. These include: testing for a specific anti-suicidal effect-separate from overall antidepressant effects-to ascertain whether ketamine might hold promise for a broader class of suicidal patients; ensuring that acute benefits of ketamine can be prolonged over a clinically meaningful timeframe; and developing a better understanding of the mechanisms by which ketamine might reduce suicide risk. Such efforts will enable the field to more accurately assess the potential of ketamine, as well as its limitations, allowing for appropriate placement within the context of comprehensive clinical care for suicide prevention.