The enormous health gap between the 'new' (eastern) and 'old' (western) parts of the EU has evolved over many decades. The epidemiological transition - that is the decrease in the relative importance of infant and early child mortality and the shift in the composition of mortality risks from communicable to non-communicable diseases - which started in the western part of the region at the beginning of the 20th century, was substantially delayed in most of eastern Europe. However, after the World War II, health improvement in the east initially out-paced the west, such that, by the mid-1960s, only 1-2 years separated the average life expectancy for both sexes between the east and west. This convergence was short-lived and it reversed dramatically between the mid 1960s and 1990. During this period, adult health status in the east stagnated or deteriorated, whereas in the west it improved steadily: by 1990, life expectancy at the age of 20 years was more than fi ve years shorter in the east for men, and more than four years shorter for women. The biggest contributors to the health gap were cardiovascular diseases and injuries. A substantial fraction of the gap can, with confidence, be attributed to the higher volume and more irregular pattern of alcohol consumption in the east, and to the delayed onset of the tobacco smoking epidemics. Much of the remainder of the gap is likely to be attributable to the composition of the diet, but the contribution of different dietary factors cannot be estimated with confidence. Leading candidates are a high consumption of saturated animal fats, a low consumption of fresh fruit and vegetables (especially in winter and spring), a very low consumption of fats supplying omega 3 fatty acids – both vegetable oils and fi sh oils rich in alpha-linolenic acid – and a high consumption of salt. Behaviours unfavourable to health did not change in the east, as they did in the west in response to the credible dissemination of scientific findings linking disease and injury risks both to individual behaviours and to the social and economic circumstances that fostered those behaviours. The eastern countries failed to equip themselves with the science and with the forms of social organisation that were needed to effectively counter epidemics of chronic disease and injury. The poor health-related behavioural determinants resulted from the institutional infrastructures based on an authoritarian, conservative and medicalised model of health, which inhibited modern approaches to social problems, an almost exclusive focus of epidemiology on communicable as opposed to non-communicable diseases, a lack of understanding and access to modern epidemiology and public health, a lack of understanding and access to evidence-based medicine, and a lack of public health education and health promotion.