Few studies have investigated the incidence rate of lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia (LPL/WM) in Asian populations. We assessed the incidence of LPL/WM using data from 13 population-based cancer registries in Japan and data from the Taiwan National Cancer registry. During 1996–2003, a total of 280 new cases of LPL/WM were recorded in Japan and 56 were recorded in Taiwan, with the median age at diagnosis being 73 and 67 years, respectively. The incidence of LPL/WM showed male predominance in both countries. Crude age-specific incidence rates increased sharply with age in both countries, especially in people >65 years. Age-standardized (to the World standard population) incidence rates per 100,000 person-years were 0.043 (0.071 for men and 0.023 for women) and 0.031 (0.041 for men and 0.020 for women) in Japan and Taiwan, respectively. Age-standardized (to the 2,000 US standard population) incidence rates in Japan and Taiwan were lower than rates reported in the literature for Asians living in the United State. A significant increasing trend was observed in the incidence over the period from 1996 to 2003 in Japan alone. This report suggests that both environmental and/or genetic factors may be involved in LPL/WM development.