Normal values and upper limits (95th percentile and 95% confidence interval of liver, spleen and portal vein size, as well as liver extensions below the costal margin were determined prospectively with ultrasound in 224 healthy subjects (renal donors). Correlation with sex, age, weight, height, and body surface area were assessed. Some correlation values were significant (r ? 0.30). The highest correlation (r=0.65 was liver AP diameter with weight. A formula to predict normal liver AP diameter was derived. Another set of subjects with established liver disease was compared with the normal means. All abnormal diameter means were at or above the 95th percentile, and the difference between the means of the normal and abnormal diameters were significant.