Abstract Purpose. Although the impact of imatinib in improving survival outcomes in chronic myelogenous leukemia (CML) patients has been widely reported, its impact on mortality from CML has not been evaluated. A survival benefit demonstrated in clinical trials does not simply translate to a decrease in mortality. To evaluate the impact of imatinib on the public health, we estimated the age-standardized mortality rate of CML patients in Japan and the U.S. using vital statistics data for Japan and data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute for the U.S. Patients and Methods. The period covered in this analysis is 1993–2008, during which 64,203 patients in Japan and 26,888 patients in nine registries in the U.S. died as a result of CML. We used joinpoint regression analysis to evaluate the significance of trends in mortality. Results. Estimated age-standardized mortality rates decreased significantly in both countries after the availability of imatinib. The annual percent changes (95% confidence interval) in the U.S. were −12.3% (−14.8% to −9.7%) for men and −11.6% (−13.1% to −10.1%) for women. In Japan, these were −20.8% (−36.2% to −1.6%) for men and −15.6% (−18.8% to −12.2%) for women. The period of change in the mortality trend seems to correlate with the period in which imatinib appeared in the two countries. The CML mortality rate in 2008 was nearly 30% that of the 1993 level. Conclusion. This is one example of the advent of a single new drug changing the picture of a single disease, CML. These results may encourage further development of drugs based on the concept of molecular targeting.