A prospective surveillance of hepatocellular carcinoma (HCC) associated with cirrhosis, using alfafetoprotein (AFP) and real-time ultrasonography (US) was carried out in 157 patients with histologically proven cirrhosis. During a two-year follow-up, 15 asymptomatic HCCs were identified. HCCs detected by these methods were at a relatively early stage, as most tumors were small (13 out of 15 less than 5 cm). US was more sensitive than AFP in the diagnosis of HCC when values greater than 400 ng/ml were considered. Patients with initial AFP values greater than 20 ng/ml developed HCC within two years more frequently than patients with values less than 20 ng/ml. A combined approach using US and AFP is suggested in our geographical area.