Serum levels of alpha-fetoprotein (AFP) may be raised for up to 2 years before clinical presentation of primary hepatocellular carcinoma (PHC). A group of people judged to be at high risk of PHC because of long-term serological positivity for hepatitis B surface antigen, ethnicity, location of residence, and a strong family history of PHC were screened for increasing levels of AFP. After 1 1/2 years of twice-yearly screening, one of them, a 19-year-old Eskimo man, had a raised AFP level, which continued to rise rapidly over the next 3 months, although the patient remained symptomless and ultrasonography, 99mTc-scan, and computerised tomography of the liver were negative. Hepatic angiography suggested a small tumour in the periphery of the right lobe of the liver, but at laparotomy the right lobe was normal. Instead a tumour was found in the lateral tip of the left lobe. The tumour, a PHC, was resected surgically, and the patient has been well in the 11 months since his operation. His serum AFP level returned to normal 2 weeks after the operation and has remained normal.