psychosocial risk factors, mental fatigue, health, stress - Many studies focused on the relationship between psychosocial risk factor at work and health outcomes. The aim of the present research is to verify the direct effect of the psychosocial work environment on the well-being of workers and the mediating effect of mental fatigue between the workplace characteristics and physical and psychological symptoms. An Italian version of the Questionnaire for Psychosocial Work Environment and Stress (PWSQ) has been administered to 314 public employees. The results showed that job demands, job control, role and social environment are related to psychological symptoms. Furthermore, the mental fatigue has a total mediating effect especially between job demand and control, and subjective wellbeing.