Crude fiber analysis does not accurately reflect the amount of dietary fiber in food materials, nor does it give a constant fraction of dietary fiber when used to compare sources in the diet. More accurate methods of estimating dietary fiber are compared. The neutral detergent method of Van Soest, modified for use with foods, was especially useful in measuring the insoluble fraction of dietary fiber. It not only provided a simple, quick method of analysis but also was useful in isolating dietary fiber for further experimentation. Water-holding capacity studies, trace mineral binding studies, and bile acid binding studies were run on the insoluble dietary fiber without interference from digestible food constituents.