Anorexia and bulimia nervosa (the eating disorders) are potentially life threatening and are becoming more prevalent. This paper reviews the effects of these disorders on dental erosion and reports a study to assess the effects of the eating disorders on the erosion of teeth relating the severity of erosion to factors such as the frequency of self-induced vomiting (SIV). One hundred and twenty-two eating disorder patients and an equal number of age, sex, and social class matched controls were studied. The study population was divided into subgroups according to the eating disorder. All the subgroups had significantly more abnormal toothwear than the controls (P < 0.005), with the differences being most marked in the SIV groups. Further analysis did not find any consistent relationships to the frequency or duration of SIV.