To assess a new computer-based method of health education for patients with bulimia and anorexia nervosa.Fifty-four patients with DSM-III-R diagnosed eating disorders were allocated randomly to one of two groups, one receiving a computer-presented health education package called DIET, the other experiencing a placebo computer-based program. Each group contained 14 anorexia nervosa patients, four anorexic patients with bulimia and nine bulimic patients. Groups were equivalent in terms of the severity of their eating disorder as measured on the Eating Disorders inventory and their estimated premorbid intelligence according to the National Adult Reading Test. Both groups were assessed before and after intervention on a questionnaire measuring knowledge of eating disorders and a questionnaire measuring attitudes to eating-disordered behaviour.The DIET group members were significantly improved when compared to the placebo group in terms of both their knowledge and attitudes towards their disorder. The patients rated the DIET program as being both easy to use and helpful.The DIET program has been found to be a resource-efficient means of health education for patients with eating disorders. Further research is required to assess whether the program has therapeutic effects in terms of behavioural improvement.