BACKGROUND: To the authors' knowledge, no previous U.S. study has examined time trends in the incidence rate of liver cancer in the high-risk Asian/Pacific Islander population. In this study, liver cancer incidence trends were evaluated in Chinese, Filipino, Japanese, Korean, and Vietnamese men and women in the Greater San Francisco Bay Area of California between 1990 and 2004. METHODS: Populations at risk were estimated by using the cohort-component demographic method. Annual percentage changes (APCs) in age-adjusted incidence rates of primary liver cancer among Asians/Pacific Islanders in the Greater Bay Area Cancer Registry were calculated by using joinpoint regression analysis. RESULTS: The incidence rate of liver cancer between 1990 and 2004 did not change significantly in Asian/Pacific Islander men or women overall. However, the incidence rate declined, although the decline was not statistically significant, among Chinese men (APC, -1.6%; 95% confidence interval [95% CI], -3.4-0.3%), Japanese men (APC, -4.9%; 95% CI, -10.7-1.2%), and Japanese women (APC, -3.6%; 95% CI, -8.9-2%). Incidence rates remained consistently high for Vietnamese, Korean, and Filipino men and women. Trends in the incidence rate of hepatocellular carcinoma were comparable to those for liver cancer. Although disparities in liver cancer incidence between Asians/Pacific Islanders and other racial/ethnic groups diminished between the period from 1990 through 1994 and the period from 2000 through 2004, the disparities among Asian subgroups increased. CONCLUSIONS: Liver cancer continues to affect Asian/Pacific Islander Americans disproportionately, with consistently high incidence rates in most subgroups. Culturally targeted prevention methods are needed to reduce the high rates of liver cancer in this growing population in the U.S.