Economists have long hypothesized that individuals make rational decisions with full information and unlimited cognitive abilities. In the expected utility theory there is no space for the emotion and when this factor is considered it is described as a source of irrationality. Cognitive psychologist have neglected for long time the role of emotions in the decision making process, too. Recent research showed that emotions and affective reactions play an important role in people's decisions. A relevant support to the claim that emotions are involved in the decision process comes from studies in neuroscience and neuroeconomics. The present paper reviews the most relevant contributions in neurosciences related to the role of emotions in decision making. In particular, the paper shows how studies with people who have brain damages in focal brain areas helped to disclose the way emotions influence people's thoughts, attitudes and preferences, sometimes in a way that improves the quality of their decisions and other times in a way that impairs it.