Background: During emergencies maladaptive behavior can reduce survival. This study compared the effects of a basic firefighter training course on 21 volunteers (with no firefighting experience) with age and gender-matched controls. Methods: Stress reactivity (salivary cortisol and anxiety) were monitored across the course: day 1 (classroom), day 2 (physical equipment training), and day 3 (simulated fire emergency). Cognitive performance (visual attention, declarative and working memory) considered important in surviving a fire emergency were measured immediately post-training or after a 20-min delay. Results: Prior to threat subjects showed an anticipatory cortisol increase but no corresponding increase in self-reported anxiety. On day 3 cortisol was higher in firefighters tested immediately after (10.37 nmol L-1 ) and 20 min after training (7.20 nmol L-1 ) compared to controls (3.13 nmol L-1 ). Differences in cognitive performance were observed post-threat, with impairments in visual declarative memory in the firefighting subjects tested immediately, and working memory impairments observed in those tested after a 20-min delay. Conclusions: Cognitive impairments were found following a simulated emergency and could explain maladaptive responses observed during real fires. Moreover, the results suggest the type of cognitive impairments observed may be time dependent, with different cognitive difficulties becoming evident at different times following an emergency.