To test a hypothesis that Japanese traditional dietary habits may be associated positively with risk of stroke and inversely with that of ischemic heart disease, a 13.5-year prospective study was conducted among residents aged 40 years and over in A-l district, Shibata City, Niigata Prefecture, Japan. Their baseline intake of nutrients and foods was assessed in July, 1977, by a food frequency method which was newly developed by the authors. Even during the follow-up period when Japanese dietary habits were considerably westernized, neither hypercholesterolemia nor obesity was related to development of stroke or ischemic heart disease. The risk of ischemic heart disease had a tendency to be low among the persons whose vegetable intake was high, and the risk of cerebral hemorrhage tended to be low among those whose intake of animal foods was high, although these relations did not reach statistical significance. This may be due to residual effects from the national privation period to the present day. © 1992, Japan Epidemiological Association. All rights reserved.