The Belfast MONICA Project carried out the joint European Economic Community WHO MONICA Project nutrition study (EURONUT) in 1985-1986 in 401 males subjects (45-64 years) using 3-day weighed records. This resulted in 356 reliable records which were analysed. The mean energy intake was 2369 Kcals (9.9 MJ) with 38% of energy (including alcohol) derived from fat (16.5% from saturated fat, 14.0% from monounsaturated fat, 4.8% from polyunsaturated fat), 14.2% from protein, 43.2% from carbohydrate and 4.0% from alcohol. The mean total fat was 100.3 g (saturated fat 43.5 g, monounsaturated fat 36.9 g, polyunsaturated fat 12.5 g), with a P:S ratio of 0.32. The sources of the different kinds of fat and cholesterol are presented as cumulative percentages of the total. This is a useful way of identifying those foods which contribute chiefly to fat in the diet, and it should have important implications for the monitoring of progress towards meeting dietary guidelines.