Several syndromes that have been characterized in terms of anorexia or appetite loss may actually be due, at least in part, to specific food aversion learning. Evidence reviewed here indicates that a number of experimental treatments, such as tumor implant and subdiaphragmatic vagotomy, that lead to anorexia in laboratory animals also lead to the development of specific aversions to the single available diet. These aversions appear to be responsible for a significant proportion of the ensuing reduction in food intake and body weight. The case for learned food aversions as a contributing factor in clinical problems of appetite loss is more speculative. However, there are certain clinical situations that provide the expected conditions for significant food aversion learning. A careful examination of dietary patterns of patients with these disorders is proposed as a first step toward evaluating the hypothesis that aversion learning is involved in the etiology or maintenance of clinically important anorexia.