Biochemical, histologic, and computed tomographic (CT) examinations of the liver were performed in 32 rabbits in which fatty liver was induced by prolonged intravenous fat infusion. In two groups of rabbits, in which 2 and 4 g/kg/day of fat emulsion was administered, respectively, posttreatment reduction in CT value of mild degree was observed, but the reduction was insignificant from the standpoint of diagnosis from CT images. In the group that received 8 g/kg/day of fat emulsion, posttreatment change in CT value was -14.9 +/- 5.1 H, a sufficient reduction for a diagnosis of fatty liver of moderate degree. No significant change in CT value was seen in the no-treatment group or in the group in which 80 ml/kg/day of normal saline solution was infused for 4 weeks. Reduction in CT value in fatty liver might be due largely to accumulation of triglyceride and cholesterol in the liver cells. Significant correlation was found between changes in CT value of the liver and degrees of histologic fat accumulation in the liver cells. Consecutive measurement of CT values of the liver during prolonged intravenous hyperalimentation is a nonaggressive method of diagnosing fatty liver.