This paper investigates the effects of September 11, 2001 terrorists' attack on decision making. It was hypothesized that after terrorists' attacks people would make more conservative and less risky decisions, as a way of compensating for the feelings of insecurity caused by the disaster. Prospect Theory is used as theoretical framework. This theory has successfully accounted for decision making under normal circumstances. To verify whether and how the terrorists' attack against the USA influenced individual decision making processes, two samples of Italian university students were tested, one month and six months after the disaster. The results show the emergence of two tendencies, which are absent during ‘normal’ historical periods: a strong, long-term lasting search for security when the outcome of a decision is perceived as a gain, and a medium-term risk avoiding behavior in the loss domain. Copyright © 2003 John Wiley & Sons, Ltd.