Vital statistics were examined for the years 1955 through 1985 for Japanese natives and United States whites to elucidate changes in cancer mortality and related antecedent patterns of life-style in these two populations. Results show that lung cancer rates are rapidly accelerating among Japanese males as a consequence of their prior history of heavy cigarette smoking. Oropharyngeal cancer rates are also rising in Japan paralleling increases in alcohol and tobacco utilization. As the Japanese life-style and diet continue to become more "westernized," the rates of malignancies of the breast, ovary, corpus uteri, prostate, pancreas, and colon also continue to rise. Nevertheless, the mortality patterns of certain malignancies, viz., laryngeal, esophageal, and urinary bladder cancer, are discrepant with their established risk factor associations, suggesting the existence of other differences in risk factor exposure between the two countries. Epidemiologists and health educators need to develop innovative international programs of investigation and health promotion with preventive impact on common malignancies associated with risk factors of life-style.