A study was conducted to determine the manner in which semisynthetic fiber-free liquid diets and complete oral liquid diets were being used in a large teaching hospital, and to determine the influence of the establishment of a dietary formulary and guidelines on prescribing. A use review of the dietary formulations was conducted both prior and subsequent to the publication of the formulary and guidelines. Ninety-five patients were monitored on 22 adult medical, surgical, psychiatric and gynecological divisions. The inappropriate or questionable orders for all types of dietary formulations decreased from 65% to 52% after the publication of the formulary and guidelines. There was a significant decrease (p less than 0.005) in orders for semisynthetic fiber-free diets, from 34 to 4, after publication of the formulary and guidelines. The guidelines and formulary appeared to have caused the decreased use of the diet formulations and to have aided in eliminating less than optimal prescribing of the products.