Summary. Commonly known risk factors for infection with hepatitis C virus (HCV) include blood transfusion, injection drug use, intranasal cocaine use, and body tattoos. We hypothesized that Asian Americans infected with HCV may not identify with these established risk factors present in Caucasians and Hispanics, and our aim was to conduct a survey of risk factors in HCV-infected patients in these ethnic groups. In this prospective study, 494 patients infected with HCV completed a detailed risk assessment questionnaire at a liver centre in Northern California from 2001 to 2008. Among subjects participating in this study, 55% identified themselves as Caucasian, 20% as Hispanic, and 25% as Asian. Asian Americans were older, less likely to smoke or consume alcohol, and have a family history of cancer compared with Caucasians and Hispanics. The laboratory profiles were similar, and genotype 1 was the most common infection in all groups (74–75%). The great majority of Caucasians (94%) and Hispanics (86%) identified with commonly known risk factors, which was in contrast to 67% of Asians (P < 0.0001). The most common risk factors in Asians were blood transfusions (50%) and acupuncture (50%). Furthermore, 74% of Caucasians and 66% of Hispanics identified more than one major risk factor, while only 20% of Asians reported having more than one risk factor (P < 0.0001). Survey for established risk factors for acquisition of HCV may be more appropriate for risk assessment of Caucasians and Hispanics, but not for Asian Americans. These findings may guide the development of HCV screening in our increasingly diverse population.