To determine the prevalence of testing for hepatitis B virus (HBV) infection in the clinical management of primary liver cancer (hepatocellular carcinoma).|The authors reviewed the records of 78 patients treated for hepatocellular carcinoma in hospitals in the Puget Sound area in 1988 and early 1989 and reviewed all 1990 U.S. death certificates on which primary liver cancer was listed.|The records of 50 (64%) of 78 hepatocellular carcinoma patients contained no evidence that the patient's hepatitis B surface antigen (HBsAg) status had been determined. In addition, of 4353 people who died in 1990 for whom the diagnosis of primary liver cancer was listed on the death certificate, HBV infection was also listed for only 136 (3%), much less than expected based on case series.|Many patients with hepatocellular carcinoma are not tested for HBV infection, suggesting that their close contacts are also not evaluated for HBV infection and the need for vaccination. Hepatitis B vaccination of close personal contacts of HBV-infected hepatocellular carcinoma patients is an important strategy for preventing HBV transmission.