During a mass survey for coronary heart disease in Tromsö, Norway, in 1974, 385 men aged 20 to 50 from one particular electoral district completed an additional questionnaire concering the intake of vitamin D from all sources (natural food, fortified food and vitamin D preparations). The average daily intake of vitamin D during the preceding 12 months was later related to the respective serum cholesterol levels. For the whole material, no association was found. When the men were grouped according to vitamin D intake above and below 2.5 mug and serum cholesterol levels above or below 250 mg %, a significant relationship appeared (using Yates's correction X2=10.3, P=0.0013 and the correlation coefficient 0.011 less than P less than 0.005).