This study tested the proposition that deficient decision making under stress is due, to a significant extent, to the individual's failure to fulfill adequately an elementary requirement of the decision-making process, that is, the systematic consideration of all relevant alternatives. One hundred one undergraduate students (59 women and 42 men), aged 20-40, served as subjects in this experiment. They were requested to solve decision problems, using an interactive computer paradigm, while being exposed to controllable stress, uncontrollable stress, or no stress at all. There was no time constraint for the performance of the task. The controllability of the stressor was found to have no effect on the participants' performance. However, those who were exposed to either controllable or uncontrollable stress showed a significantly stronger tendency to offer solutions before all available alternatives had been considered and to scan their alternatives in a nonsystematic fashion than did participants who were not exposed to stress. In addition, patterns of alternative scanning were found to be correlated with the correctness of solutions to decision problems.