For use in microscopic detection of fecal fat due to malabsorbtion. Sudan Black IV Stain, also known as scarlet red, was introduced by Michaelis in 1901 as a fat stain.(6) It is a dimethyl derivative of Sudan III, which makes it a deeper and more intense stain, yet it has similar physical properties and is fat soluble.(6) This stain has been widely used as a screening method, because it is easy to use and correlates well with quantitative methods.(4) Sudan Black IV Stain is used as a qualitative method to detect the presence of fecal fat. Normally the stool will not contain more than 20 grams of fat daily.(7) In the case of steatorrhea, fat malabsorbtion occurs, and greater quantities of fat are detected in the stool. This procedure, when performed carefully and consistently, is a simple method of detecting this condition in the patient.