Sera from 185 patients admitted to hospital in Malawi with acute and chronic liver disease were tested for the following serological markers of hepatitis-B infection (HBV): hepatitis-B surface antigen (HBsAg) and its antibody (anti-HBs), HBe antigen (HBeAg) and its antibody (anti-HBe), and antibody to hepatitis-B core antigen (anti-HBc). Control groups consisted of patients without liver disease, students and blood donors. HBsAg was detected in 73%, 54·8% and 64% of patients with acute hepatitis, cirrhosis and hepatoma, respectively. 16% of patients with tropical splenomegaly syndrome (TSS) and 14·6% of patients with schistosomiasis, 9·5% of patients without liver disease, 1·4% of students and 7·6% of blood donors were HBsAg positive. Unexpectedly, 72·3% of HBsAg-positive specimens appeared to carry both major antigenic determinants ( ady). HBeAg was detected in 15·8% and anti-HBe in 13·1% of patients with acute HBsAg-associated hepatitis, these determinants being detected less frequently than in sera from patients with HBsAg-associated hepatitis in the UK. HBeAg or anti-HBe were rarely detected in patients with hepatoma. With the exception of students and blood donors, over 80% of the Malawian study population had markers of current or previous HBV infection in their sera. Anti-HBc occurred most frequently in patients with hepatitis, cirrhosis and hepatoma, their geometric mean titres (GMTs) being 67·6, 160·1 and 211, respectively. The GMTs of patients with TSS, schistosomiasis and non-hepatic disease were 2·0, 4·6 and 2·3, respectively.