OBJECTIVE: In a longitudinal study design to analyze the development of burnout at worksites and to study the effect of interventions intended to reduce the level of burnout at individual level. METHODS: At baseline the study, sample consisted of 1024 individuals divided at six organizations and 18 worksites in the human service sector. Four different types of interventions were identified: external and internal reorganizations, educational days, and consultancy. Burnout defined as work related, client related, and personal burnout was measured by means of the Copenhagen Burnout Inventory at baseline and at first and second follow-up during the years 1999 to 2005. RESULTS: We found a weak but statistically significant negative effect of reorganizations after adjusting for potential confounders and mediators defined as changes in the psychosocial working conditions. CONCLUSION: The four types of interventions did not reduce the level of burnout in our study.