Subclinical hepatocellular carcinoma (SCHCC) is defined as HCC without obvious HCC symptoms and signs. During 1958-1991, 391 patients with SCHCC were analyzed. In the entire series, 1) 67.3% was detected by natural population sereening using alpha-fetoprotein (AFP) serosurvey, while the others were discovered by high-risk population screening or regular health checkup using AFP and/or ultrasonography (US); 2) AFP>20 ug/L was found in 77.6% of patients; 3) serum hepatitis B surface antigen (HBsAg) was positive in 68.9; 4) associated liver cirrho-sis occurred in 89.1%; 5) the median tumor size was 5 cm, and limited resection was performed in the majority (71.3%); 7) re-resection for sub-clinical recurrence was done in 44 patients; and 8) cytoreduction and sequential resection was carried out in 13 patients with unresectable SCHCC. Comparison between SCHCC and clinical HCC (n=1, 251) revealed higher resectability(81.4% vs, 46.8%), lower operative mortality (1.9% vs. 6.0%), and higher 5-year survival (entire series; 50.7% vs. 20.6%; resection: 60.5% vs. 36.8%). It is concluded that the study of SCHCC has resulted in marked improvement of ultimate outcome of HCC; screening in high-risk populations using AFP and/or US, limited resection, and re-resection for subclinical recurrence are some of the key features.