To assess the features of multicentric occurrence in hepatocellular carcinoma, we analyzed 10 of 72 patients (14%) who had undergone hepatic resection for hepatocellular carcinoma from May 1989 to October 1992 both clinically and pathologically. The multicentric occurrence of hepatocellular carcinoma was defined among the simultaneously detected small tumors as (a) at least one tumor consistingof extremely well-differentiated (grade I) hepatocellular carcinoma growing in a replacing pattern or (b) one of a group of hepatocellular carcinomas growing in an area of adenomatous hyperplasia. Of the 10 patients, the tumors in 9 were diagnosed as synchronous multicentric hepatocellular carcinomas, whereas the tumor in 1 was considered metachronous. All patients had cirrhosis; one of them had hepatitis B virus infection and nine patients had HCV infection. The inflammatory findings in the parenchyma were determined on the basis of serum enzyme values (AST, 89 2 27 IU/L; ALT, 96 f 43 IU/L). One or two tumors in 9 of 10 patients had thin trabecular or trabecular patterns showing replacing growth. In addition, one of the two tumors in two of nine patients was observed growing in areas of adenomatous hyperplasia Recurrences were found in 4 of 10 patients. The 3-yr disease-free survival rate was 23%. Multiple recurrences were recognized in the two patients, and in the patients who underwent repeat surgery, grade I tumors were also found. Even though these tumors were small and well-differentiated, the recurrence rate was high. Therefore to detect the recurrence of metachronous multicentric hepatocellular carcinoma at an earlier stage, careful follow-up after surgery should be carried out. (HEPATOLOGY 1994; 19889-894.