Southeast Asians have higher rates of liver cancer than any other racial/ethnic group in the United States. Chronic carriage of hepatitis B virus (HBV) is the most common underlying cause of liver cancer in the majority of Asian populations. Our objectives were to describe Vietnamese Americans’ awareness of hepatitis B, levels of HBV testing, and knowledge about hepatitis B transmission; and to compare the HBV knowledge and practices of men and women. A community-based, in-person survey of Vietnamese men and women was conducted in Seattle during 2002. Seven hundred and fifteen individuals (345 men and 370 women) completed the questionnaire. Eighty-one percent of the respondents had heard of hepatitis B (76% of men, 86% of women) and 67% reported HBV testing (66% of men, 68% of women). A majority of the participants knew that HBV can be transmitted during sexual intercourse (71% of men, 68% of women), by sharing toothbrushes (67% of men, 77% of women), and by sharing razors (59% of men, 67% of women). Less than one-half knew that hepatitis B is not spread by eating food prepared by an infected person (46% of men, 27% of women), nor by coughing (39% of men, 25% of women). One-third of our respondents did not recall being tested for HBV. Important knowledge deficits about routes of hepatitis B transmission were identified. Continued efforts should be made to develop and implement hepatitis B educational campaigns for Vietnamese immigrant communities. These efforts might be tailored to male and female audiences.