The objective of this study was to characterize better the cancer burden among Asian subgroups in California. Nearly 3.7 million Asians reside in California, and no other state has as many Asians. Cancer statistics for Asians often are combined with statistics for Pacific Islanders, and rates for subgroups are not often examined, because most states do not have a large enough population. Asians are affected disproportionately by certain cancers, such as stomach and liver cancers. The California Cancer Registry, a population-based cancer registry, has collected data, including race/ethnicity data, since 1988. The 5-year, average, annual, age-adjusted cancer incidence and mortality rates from 1997 through 2001 were calculated for 5 Asian subgroups: Chinese, Filipino, Japanese, Korean, and Vietnamese. Cancer incidence and mortality varied greatly. Incidence rates for all sites combined among males varied from a low of 318.6 per 100,000 for Chinese to a high of 366.0 per 100,000 among Japanese. For females, rates ranged from 236.6 per 100,000 among Koreans to 302.4 per 100,000 among Japanese. Mortality rates also varied by Asian subgroup. Presenting one statistic for Asian/Pacific Islanders did not provide an accurate depiction of the cancer burden among the different Asian subgroups. Acculturation will continue to affect the patterns of cancer incidence among Asian subgroups in California. Cancer 2005. (c) 2005 American Cancer Society.