Serum levels of soluble forms of intracellular adhesion molecule-1 (sICAM-1) and lymphocyte function-associated antigen-3 (sLFA-3) in 122 patients with chronic liver disease including hepatocellular carcinoma (HCC) were measured by enzyme-linked immunosorbent assays. Serum levels of sICAM-1 in patients with HCC were significantly higher than those of chronic hepatitis (CH) and cirrhosis. On the other hand, serum levels of sLFA-3 in patients with HCC were almost the same as those of cirrhosis. Western blot analyses showed that molecular sizes of sICAM-1 and sLFA-3 detected in the sera were 90 kd and 50 kd, respectively, indicating that both molecules include whole extracellular domains. In patients with HCC, circulating sICAM-1 levels were significantly (P < .001) correlated with tumor volume (r = .50), total bilirubin (r = .38), serum aspartate aminotransferase levels (r = .51), and gamma-globulin (r = .63). Furthermore, serum sICAM-1 levels were significantly elevated in patients with multiple HCC (tumor number > 3) or HCC with tumor embolus in the first branch or trunk of portal vein. Survival periods were analyzed in relation to serum sICAM-1 levels in patients with HCC who had been treated by transcatheter arterial chemoembolization. The HCC patients with < 1,000 ng/mL of serum ICAM-1 showed significantly (P = .0005) longer survival than those with higher levels of the molecule. The same results were obtained when only patients with moderately differentiated HCC were analyzed (P = .02). Analyses by Cox's proportional hazard model showed that sICAM-1 is a significant (P = .032) prognostic factor for patients with HCC.(ABSTRACT TRUNCATED AT 250 WORDS)