Susto is a both a culture bound syndrome and an idiom of distress with many variations around a consensus fundamental core set of symptoms – mostly somatic but some psychological – caused mostly by fright and stress. It is found mostly in Central and South America, but also among Mexican American populations, and to a lesser degree in Spain; it does not occur throughout the whole Spanish-speaking world. The DSM IV only lists susto in Appendix I and relates it to Major Depressive Disorder (MDD), Post Traumatic Stress Disorder (PTSD), and lastly to Somatoform Disorders (SD) which have no apparent medical cause. Anthropologically, it has been studied for associations to physiological symptoms via biomarker analyses, with positive correlations, but also reported by some populations to be a causal factor in major debilitating illness (mostly diabetes, but also cancer) and even death, where research has provided tentative evidence that neither is the case. Herein: causes, treatments, and cultural descriptions.