Low-dose infusion of ketamine may have rapid antisuicide properties. Such a treatment may therefore be useful in the general hospital to prevent suicide in an environment that cannot be made safe enough. We report on the use of ketamine as an efficient, well-tolerated treatment for persistent suicidal ideation in a patient hospitalized in a general hospital after a severe suicide attempt. Based on data in the literature, we suggest that the benefit-risk ratio for ketamine use in such a context is highly favorable.