An analysis was made of the possible influence of nutritional factors on the etiology of multiple sclerosis in Gorski Kotar (Croatia), a high-risk zone for this disease. A total of 46 MS patients and 92 controls, native-born residents of the area studied, participated in a case-control study. The questionnaire comprised 51 questions concerning dietary habits. An odds ratio (OR) estimate was obtained for all the factors which were more frequently found in the patients than in the controls. Large differences were found in the daily consumption of different quantities of full fat unskimmed milk (OR 21.7; chi 2 42.34; LL 7.12), potatoes with lard and fresh or smoked meat (OR 20.7; chi 2 15.52; LL 2.72), and new potatoes (OR 20.7; chi 2 15.52; LL 2.72). The consumption of unpasteurized milk, animal fat, smoked meat and potatoes are nutritional risk factors which could have an influence on the severity of primary demyelinization in a high-risk area for multiple sclerosis.