A prospective study was conducted among customers of health food shops and members of societies interested in health foods. A total of 10,896 persons were followed for 10-12 y, including 4671 vegetarians and 6225 nonvegetarians. Mortality from ischemic heart disease (IHD) was significantly lower in the vegetarians than in the nonvegetarians; the difference was especially marked among the men. In a subset of 300 subjects, serum cholesterol and body mass index were lower in the vegetarians than in the nonvegetarians but there were no consistent differences in blood pressure between the two groups. Vegetarianism seems to confer protection against heart disease