[en] We examined the noncancer disease mortality for 86,572 atomic bomb survivors with dose estimates in the Radiation Effect Research Foundation's Life Span Study cohort between 1950 and 1990. There are 27,000 noncancer disease deaths and show a statistically significant increase in noncancer disease death rates with radiation dose. Increasing trends are observed for diseases of the circulatory, digestive, and respiratory systems. Rates for those exposed to 1 Sv are elevated about 10%, a relative increase that is considerably smaller than that for cancer. However, because noncancer deaths are much more common than cancer deaths, the absolute increase in noncancer rates is large. The estimates of the number of radiation-related noncancer deaths in the cohort to date are 50% to 100% of the number for solid cancer. There remains uncertainty about the shape of the dose-response. In particular, there is considerable uncertainty regarding risks in the range below 0.2 Sv of primary interest for radiation protection. The data are statistically consistent with curvilinear dose response functions that posit essentially zero risk for doses below 0.5 Sv, but there is no significant evidence against linearity. While the ERR for those exposed as children tends to increase with attained age, there is no statistically significant dependence of ERR on age at exposure or attained age. We also tried to estimate the lifetime risk, allowing for competing risks of cancer mortality. Especially we considered the impact of competing radiation risks since both cancer and noncancer mortality are in part radiation-related. These findings, as they are based on death certificates, have their limitation. However, the present findings can not be explained by biases due to misclassification of the cause of death and confounding factors. In the future, it will be necessary not only to continue mortality follow-up, but also to conduct a clinical study as well as animal experiments and biological research for elucidating the mechanisms of the effect of radiation on noncancer diseases. (author)