A clinical feature of bile acid deficiency states is the malabsorption of fat. A differential diagnostic approach was taken in over 200 patients with disordered bile metabolism who were selected from the literature. This approach is based upon the understanding of the normal process of fat absorption coupled with the application of four commonly available malabsorption tests. In contrast to other malabsorptive states, bile acid disorders are characterized clinically by a milder form of steatorrhea and normal or near-normal findings with respect to other major absorption tests. These characteristics should facilitate their diagnosis and eventual treatment.