Burnout is a mental condition described as being a result of long-term stressors commonly related to psychosocial factors at work. The aim of the present study was to investigate longitudinal relationships between job demands, decision authority, effort and reward, and symptoms of burnout, as well as the joint effects of job demands and decision authority, and of effort and reward. The data came from a four-wave longitudinal cohort study of Swedish health care workers. Longitudinal associations were analysed using mixed effects regression models with random intercept. The concurrent analysis showed that demand and decision authority, as well as effort and reward, were associated with symptoms of burnout over time. Evidence of the lagged effects of workplace factors on burnout symptoms was limited to reward. No clear effect modification was found. An increase in unfavourable working conditions implied increasing scores on the burnout measure over time. The concurrent effects of job demands, decision authority, effort and reward on symptoms of burnout were seen. The evidence of lagged effects was limited to the low-reward condition. Regularly monitoring these work environment conditions at workplaces can help identify risk situations for burnout and thus be useful in the prevention of work-related mental illness. Lastly, a new approach to defining the risk groups was proposed, which is consistent across different populations and time points.