This study was performed on 18 police officers, in order to evaluate relations between behavior and the activity of the main hormonal systems implicated in stress management. All subjects were male volunteers with more than 2 years on the job, a type A psychological profile according to Friedman and Rosenman, suffering from no mental or physical illness. The experimental setting used to study the role of different stress factors consisted of a series of tests that re-created stressful situations that the subject might encounter in his job. The study showed that during stressful states, not only did peripheral secretion of catecholamines increase, but that the ratio of epinephrine to norepinephrine was a determinant factor. Epinephrine secretion which was elevated at the beginning, decreased when the stressful situation was clarified or controlled, whereas norepinephrine secretion remained elevated as long as the subject had to remain alert. Cortisol secretion seemed to depend upon anticipation of the stressful event more than its actual happenning.