The association of cigarette smoking habits and social class with nutrient intake was investigated in 162 men aged 45-54 using a 7-d weighed dietary record. Cigarette smokers had a significantly lower intake of fibre and polyunsaturated fatty acids and a lower P:S ratio than non-smokers. Fibre intake was lower in men in the manual compared to the non-manual group but smoking was a more powerful influence than social class. The differences in nutrient intake were accompanied by differences in the consumption of polyunsaturated margarines and cereal-containing foods. These results should be considered in the explanation of the increased incidence of coronary heart disease in smokers.