Hepatocellular carcinoma (HCC) is an important cancer. It occurs more often in men than women, and occurs mostly in people 50 to 60 years old. HCC has not been previously reported in a young HIV-seropositive patient in Thailand. We documented a very rare case of HCC in a 33 year old man. He was diagnosed and treated as Salmonella septicemia and tuberculosis. However, additional diagnosis based on pathological study disclosed a moderately differentiated HCC. Immunohistochemical study of the liver tissue was positive for hepatitis B surface antigen (HBsAg).