The importance of alanine aminotransferase (ALT) levels in the progression of hepatitis B virus (HBV) infection remains a subject of debate. This study sought to identify independent risk factors involved in development of hepatocellular carcinoma (HCC), particularly in patients with chronic HBV infection who have normal ALT values. Data from 381 consecutive hepatitis B patients were analyzed with average ALT integration values < or = 40 IU/L and follow-up periods of > 3 years. Integration values were calculated from biochemical tests, and serological markers associated with the cumulative incidence of HCC were analyzed. HCC developed in 17 of the 381 patients (4.5%) during the follow-up period. Male sex (hazard ratio, 6.011 [95% confidence interval: 1.353-26.710], P = 0.018), high HBV-DNA levels (> or = 5.0 log copies/ml; 5.125 [1.880-13.973], P = 0.001), low platelet counts (< 15.0 x 10(4)/mm(3); 4.803 [1.690-13.647], P = 0.003), and low total cholesterol levels (< 130 mg/dl; 5.983 [1.558-22.979], P = 0.009) were significantly associated with greater incidence of HCC development. High HBV-DNA levels and low platelet counts are associated with the development of HCC in patients infected with hepatitis B who have normal ALT values. Therefore, maintenance of low HBV-DNA levels is important for the prevention of HCC in patients with low platelet counts, particularly in patients whose ALT values fall within the current normal range.