Fine needle biopsy specimens from patients with diseases accompanied by fatty liver have been analysed for triglycerides, phospholipids, free and esterified cholesterol. In selected cases the fatty acid composition of triglycerides was determined. The concentration of the lipids was not found to vary with the fundamental disease. A positive correlation between esterified cholesterol and triglycerides was verified in the presence of a moderately, but not of a severely, fatty liver. An association between esterified cholesterol and the surface area of fat droplets in the liver is suggested.