This study describes the evolution of the concept of health in Italian occupational health legislation (1900-2001). Mental health dimensions at work (such as reduction in monotony and repetitiveness, mental risks in pregnancy and so on) were introduced only recently. This can be explained with: 1) poor working conditions; 2) the delay of the occupational health community in including mental health in the concept of health; 3) the gap between scientific knowledge of risk factors for mental health and legislation aimed at prevention.