Attenuation values were obtained from 50 CT examinations of the upper abdomen. A normal range of values, obtained for the organs in the upper abdomen, was compared with patient size and age. Rank ordering according to the mean attenuation values was also performed. The most significant finding was that the liver normally had the highest attenuation value of any of the viscera measured. When another organ in the upper abdomen had a mean value greater than that of the liver, this reflected severe systemic disease.