The incidence rate and the death rate of cystic fibrosis (CF) in Japan were analyzed using Japanese Vital Statistics data for the period 1969-1992. The incidence rate was 3.1 per million live births during the period 1969-1980, where the rate was 1.5 times higher in rural than urban areas. The proportion of deaths from CF under 5 years old was 82% and under 20 years old was 94%. Overall death rates of CF per million population under 20 years of age were 0.15 for males and 0.10 for females, the difference being significant; the death rate was also significantly higher in males (2.2 per million) than females (1.3) in the first year of life. The death rate decreased from the period 1969-1973 to the period 1989-1992 for males. There were geographical variations in the incidence and the death rates among nine districts. These rates of CF were observed with the highest being in Hokkaido and the lowest in Okinawa. The death rate from CF was negatively correlated with the average temperature. The death rate was higher in rural than in urban areas during the period 1969-1985. The mean age at death from CF was 3 years for both sexes during the period 1969-1985, the value has been increased since 1979.