Shift work is affecting 20% to 25% employees and is becoming increasingly prevalent in contemporary life all over Europe and USA. It is associated with several health problems, such as e.g. metabolic syndrome, diabetes mellitus and cardiovascular disease. These diseases are possibly due to an impairment of biological rhythm. The metabolic syndrome is a complex of interrelated risk factors for cardiovascular disease and diabetes. Higher prevalence of the metabolic syndrome has been demonstrated among shift workers. Rotating shift work has an impact on each component of metabolic syndrome. Shift work might also have an impact on metabolic variables, and be a risk factor for type 2 diabetes. Only a few studies reported prevalence of impaired glucose metabolism and diabetes mellitus in relation to shift work. There is rather strong evidence in favour of association between shift work and coronary heart disease and that has been repeatedly demonstrated during over 20 years of research. Recent data increasingly reveal relations between shift work and plasma resistin, ghrelin, leptin and adiponectin.