Approximately 4 million Americans are infected with the hepatitis C virus (HCV). Most patients with hepatitis C have no symptoms until cirrhosis is established. Thus, initial diagnosis and management of hepatitis C rely on primary care physicians identifying and screening high-risk individuals. We administered a survey to 1,233 primary care physicians in a health maintenance organization (HMO) in April 1997 to assess their knowledge of the risk factors for HCV infection and approach to the management of 2 hypothetical HCV antibody-positive patients, 1 with elevated and the other with normal alanine transaminase (ALT). Four hundred four (33%) physicians returned the survey. Ninety percent of respondents correctly identified the risk factors for HCV infection, but 20% still considered blood transfusion in 1994 as a significant risk factor for HCV infection. Sixty-two percent of respondents would refer HCV antibody-positive patients with abnormal transaminase levels, but 33% would follow these patients themselves, even though none of the respondents had treated any hepatitis C patient on their own. Forty-three percent of respondents overestimated, while 29% did not know the efficacy of interferon treatment. Sixty-five percent of respondents would retest patients for HCV antibody, regardless of risk factors and transaminase levels. We found that most primary care physicians correctly identified the significant risk factors for HCV infection and appropriately managed the 2 hypothetical patients, but there was considerable confusion about the use of HCV tests and the effectiveness of treatment. Educational programs for primary care physicians are needed to implement hepatitis C screening and to initiate further evaluation and management of those who test positive.