A community-based project for the prevention of cardiovascular diseases was undertaken in 1989 in a rural Danish municipality (Slangerup) with about 8000 inhabitants. Project goals were to draw attention to project activities and improve smoking, eating and exercise behaviours. The intervention was planned using the social learning theory, a communication-behaviour change model and community organisation principle. The strategy used for intervention involved both mass communication and active involvement of the local population in group activities. The objectives of the intervention were assessed by data obtained from representative cross-section surveys in intervention and a control area at baseline (1989) and one year later. More respondents in the intervention (82%) than control (67%) area were aware of local health projects. Ten % reported that they stopped smoking within the last year, 39% ate less fat, and 28% did more exercise, with no differences between intervention and control area. Several explanations are proposed for the limited effect of the project on behaviours. One possible explanation is that the project almost ended up being a pure mass media campaign which may increase awareness, but, as experience shows, may have limited influence on adoption of new behaviour. The Danish population around 1990 is very well informed and educated in this field due to earlier nationwide interventions. No further behavioural effects are obtainable with mass media campaigns.