Ultrasonograms taken within 24 h before liver biopsy were evaluated retrospectively for fatty infiltration of the liver in 155 non-ascitic patients with liver diseases. Relatively high amplitude echoes of the liver as compared with the kidney were observed in all of 33 patients whose fatty infiltration of the liver occupied more than 10% of each lobule or pseudolobule irrespective of etiology. Among such patients, loss of echoes from the gallbladder wall was additionally found in 18 of 19 cases uncomplicated by hepatic fibrosis, but only in 3 of 14 cases with this complication. We conclude that fatty infiltration without fibrosis in the liver may be differentiated from that with fibrosis by ultrasonic examination.