Introduction We investigated the chronological change in cause-specific mortality-temperature pattern, because this is necessary for projecting health effects of the global warming. Methods The materials we used were computerized data sets of death certificates, population and meteorological factors from 1972 to 1994. We calculated daily mortality rates from neoplasm, circulatory diseases and respiratory disease for 65+ years old males and females. Because the revision of International Classification of Diseases may affect the cause-specific rate and because we are interested in chronological change in mortality pattern, we divide the study period into three parts, i.e., 1972–1978 (ICD-8), 1979–1986 (ICD-9), 1987–1994 (ICD-9). Daily maximum temperature is the measure of exposure in this study, because we are interested in the global warming. The unit of observation we chose was prefecture. For each prefecture, daily cause-specific mortality rates and daily maximum temperature measurements were obtained. To observe the relation between these two variables, we applied non-parametric regression model using locally weighted regression smoother (LOESS) with the span being 0.4. We chose 0.4 because the fitted curve generally showed only one local minimum value for circulatory and respiratory diseases; we considered natural that the mortality rate would be high for extremely high or low temperature and low for the moderate temperature. Results and Discussion Circulatory disease and respiratory diseases showed similar mortality-temperature relation, i.e., colder days entailed higher mortality in general (with some modifications) but the chronological change was different; former was decreasing and the latter was increasing. We expected that the temperature dependency for circulatory and respiratory diseases would have been less obvious for the more recent period, but we did not see such pattern. Also, in some instances, the extremely high temperature level yielded higher mortality rates than the moderate temperature level. However, it is not restricted to later years when the air-conditioning was much more popular. These findings suggest that the effect of air-conditioning on the mortality pattern would be small, if any. The optimum temperature, at which the daily mortality rate is the smallest, appeared higher in the warmer climate prefectures than in the colder climate prefectures. This would be due to adaptation, both physiological and non-physiological. Neoplasm showed no consistent pattern. This is understandable that most of the terminally ill patients with neoplasm would be hospitalized, and the hospital buildings are usually air-conditioned. Conclusions We considered that it was necessary to take the above change in mortality pattern into account when we project the health effect of the global warming. Also, we considered that evaluation of the adaptation would also be important in the projection.