Abstract Abstract 2695 Background: Malignant lymphomas (ML) are heterogeneous groups that the detailed classification is evolving dramatically. An incidence of malignant disease in certain population reflects cumulative exposure to environment, genetics and their combination overtime. Therefore, a comparison of incidences in various population and their secular trends is very helpful to understand etiology of disease. The aim of this study is to assess the incidence and the trend of each ML subtypes and to evaluate the difference between Japan and US. Materials and Methods: We used the data from a population-based cancer registry in Japan and from the Surveillance Epidemiology and End Results (SEER) program 9. Registry data of the US, SEER 9 included 95,155 cases and the data of Japan included 48,658 cases. The period covered in this analyses was 1993 to 2006 in Japan and 1993 to 2008 in the US. Rates of sex-specific, age-standardized incidence with 95% confidence intervals were estimated and standardized by age-adjustment according to the world standard population. We also estimated the annual percent change using joinpoint regression analysis and evaluated the significance of the trend. Results: The overall age-standardized incidence rate of all malignant lymphomas per 100,000 in 2006 was 22.4 for males and 16.0 for females in the US, 7.4 for males and 4.9 for females in Japan. The incidence is higher in the US than Japan with most of the subtypes especially for the nodular sclerosis HL, CLL/SLL and FL. In general, B-cell lymphomas showed large difference in incidence while T-cell lymphomas (TCL) showed similar incidence between Japan and the US. The total numbers of ML are constantly increasing in Japan but not in the US as shown in the figure {annual percent change (95%CI), Japan; +2.6% (2.1, 3.1), US; +0.2% (−0.0, 0.4)}. As for details, follicular lymphoma, mantle cell lymphoma, Burkitt lymphoma and the total numbers of TCL are constantly increasing in both countries. Conclusion: In conclusion, we showed the marked difference in the incidence and the trend of hematologic malignancies between Japan and the US. The incidence of hematologic malignancies is lower in Japan than the US, but is increasing significantly. The most remarkable difference in the incidence was seen with nodular sclerosis HL, CLL/SLL and FL which was consistent with previous reports. Even with the TCL, the incidence seems to be similar to higher in the US except for the ATLL. The improvement in the quality of cancer registry systems and the organization of these registries between countries enables us to unite the data worldwide that will bring us new insights. Solid line and circle are the data of the US. Dashed line and hollow circle are the data of Japan. Disclosures: No relevant conflicts of interest to declare.