During the period 1982–1992 changes in lifestyle and knowledge of the risk factors for ischaemic heart disease (IHD) in Danish adults were assessed by comparing questionnaire data collected in 2 independent cross-sectional studies. In 1982 the participation rate was 79% from 4,807 randomly selected men and women aged 30, 40, 50 and 60 years. In 1992 it was 73% from 2, 226 randomly selected men and women of similar ages. From 1982 to 1992 the proportion of participants stating that exercise, eating a low-fat diet, avoiding being overweight and not smoking reduces the risk of IHD increased. During the same period, the proportion of smokers, of men who did not eat vegetables daily and of men and women who used butter, fat or margarine daily decreased. The changes were seen predominantly among salaried employees and those with a vocational education and social differences were enhanced. The changes in knowledge and lifestyle reflect the topics on which the general educational effort has focused and are in accordance with results from comparable studies in the USA. Apparently, however, only in the higher social classes is the acquired knowledge associated with a change in lifestyle.