The case of a 70-year-old man with clinically-compensated alcoholic liver cirrhosis is illustrated. His serum alpha-fetoprotein level was on the increase but Ultrasonography and Magnetic Resonance detected no focal lesion of the liver. Five months after Ultrasonography, Computed Tomography and Magnetic Resonance were performed because the patient's alpha-fetoprotein level indicated hepatocellular carcinoma, but none of these tests succeeded in locating the neoplasm. Digital subtraction angiography was performed and only then was a small hepatocellular carcinoma revealed under the diaphragm. The patient underwent transcatheter arterial chemo-embolization with the result that the alpha-fetoprotein level dropped immediately and is still normal after 15 months. The case described is a model of what the ideal function of a marker of neoplasia should be, namely early detection, and subsequent precise confirmation of the continuing efficacy of the treatment adopted.