The aim of the present study was to investigate the result of general practitioners' advice to men with increased risk of ischaemic heart disease (IHD). The study was a multipractice study with 65 general practitioners in the county of Aarhus. The intervention group included 169 40-49 year-old men with high and increased risk of IHD, 125 men with a moderate risk of IHD were selected as the control group. The intervention was a health talk and advice based on the men's individual risk-score for IHD. Six months after the examination the effect of the intervention was evaluated as change in the men's risk-score for IHD. There was a significant decrease in the incidence of risk factors for IHD in both the intervention and the control group, but the decrease was the same in the two groups. The conclusion of the study is that the change in the risk factors and the risk-score for IHD was mainly due to the Hawthorn effect and regression towards the mean. The general practitioners' advice had no additional effect on the men's health behaviour.