Serum ferritin levels were determined by 2-site radioimmunoassay in 20 normal controls and 77 patients with acute viral hepatitis (AVH), chronic active hepatitis (CAH), liver cirrhosis (LC) and primary liver cancer (PLC). The results were as follows: 1) In AVH, CAH and LC, serum ferritin levels were found to be significantly raised with wide range, and good correlation was demonstrated between the serum ferritin levels and serum transaminase activity, which suggested that elevation of the serumz ferritin level was due to leakage of storage ferritin by hepatic necrosis. 2) In patients with liver disease, no correlation could be demonstrated between the serum ferritin levels and transferrin saturation ratio and absence or presence of occult blood in stool. In patients with liver disease it appeared impossible to use serum ferritin level as indrect measurement of storage iron. 3) In the differential diagnosis of PLC from other liver diseases, serum ferritin measurement showed low sensitivity, low predictive value and relatively high false positivity.