Investigated the role of the amygdala in decision making under ambiguity and risk. Three patients with Urbach-Wiethe disease (aged 17, 38, and 50 years), suffering from selective bilateral damage to the amygdalae, as well as 20 matched and representative controls (mean age 30 years) were assessed with an extensive neuropsychological test battery measuring executive functions. The patients and controls also completed two decision-making tasks. The Iowa Gambling Task required decisions under ambiguity, whereas the Game-of-Dice Task required decisions in risky situations. In addition, skin conductance responses (SCRs) were recorded as indicators of emotional reactivity. Patients were shown to have lower scores and SCRs than controls in both decision-making tasks. Moreover, patients with additional deficits in executive functioning showed an even lower performance with decisions under risk. It is concluded that damage to the amygdala impairs the emotional feedback processes required to learn to make advantageous decisions in uncertain and risky conditions. Moreover, the additional cognitive component involved in risk decisions is thought to be compromised when executive functioning is impaired.