BackgroundPossible health effects for employees of efforts to improve the psychosocial competence of managers have not been studied scientifically in the past.ObjectiveTo explore how efforts to improve management will change the work environment and health of the employees.MethodsManagers of the experimental department in a large insurance corporation underwent 2-hour biweekly training sessions for 1 year—altogether, 60 hours. A control group of employees in other departments in the corporation not affected by the modification was followed with the same assessments. Morning blood samples for the assessment of serum cortisol were collected both at baseline and after 1 year in 155 participants in the experimental group and in 147 subjects in the control group. Liver enzymes and lipids were also assessed. In the questionnaire part of the 1-year follow-up study, there were 119 participants in the experimental group and 132 in the control group.ResultsWhen repeated-measures ANOVA was used, a significant interaction effect was found for the level of serum cortisol; serum cortisol levels were decreased in the intervention group and wereunchangedin the control group (ANOVA two-way interaction,p= .02; after exclusion of the managers,p= .005). A significant interaction effect was also observed for decision authority, with increased decision authority in the intervention group and, conversely, a decreased level in the control group (p= .001; after exclusion of managers,p= .02).ConclusionsThe study indicates that a moderately intensive psychosocial manager program lasting for 1 year can be beneficial for the employees with regard to both lowered serum cortisol and improved authority over decisions.