This paper discusses how psychological stress disturbs decision making during technological crisis and disaster, and how to prevent this from happening. This is exemplified by scientific studies of a Norwegian large scale accident involving hazardous material, and of handling the far-off effects of the nuclear disaster at Chernobyl. The former constitutes an operative level of crisis management, whereas the latter involves crisis management at the strategic and political level. We conclude that stress had a negative effect on decision making in both cases.