The relations between coffee and dietary habits and between coffee, dietary habits, and serum cholesterol were examined in 11,912 men and 12.328 women aged 35-49 years in the Cardiovascular Disease Risk Factor Study in Oppland, southern Norway, 1976-1978. Dietary data are based on results from a self-administered questionnaire. In both sexes, the dietary pattern of persons with a high coffee consumption differed from that of persons with a low coffee consumption: Heavy coffee drinkers had a higher consumption of bread, potatoes, and butter or margarine per slice of bread and more frequent use of hard margarine; men had a higher consumption of eggs and a lower consumption of skim milk. These results suggest a higher total food and fat consumption and a lower ratio of polyunsaturated to saturated fatty acids among heavy coffee drinkers. However, only 20% of the variation in coffee consumption was explained by dietary and lifestyle variables. The study confirmed a positive relation between serum cholesterol and use of butter or hard margarine (p less than 0.001) and between serum cholesterol and coffee consumption (p less than 0.001). Bread consumption and milk consumption were negatively correlated to serum cholesterol. The negative association with skim milk was significant only in women (p less than 0.01).