OBJECTIVE--To test the short term efficacy of a self directed treatment manual for bulimia nervosa. DESIGN--Randomised controlled trial of the manual against cognitive behavioural therapy and a waiting list. SETTING--Tertiary referral centre. SUBJECTS--81 consecutive referrals presenting with bulimia nervosa or atypical bulimia nervosa. MAIN OUTCOME MEASURES--Frequency of binge eating, vomiting, and other behaviours to control weight as well as abstinence from these behaviours. RESULTS--Cognitive behavioural treatment produced a significant reduction in the frequency of binge eating, vomiting, and other behaviours to control weight. The manual significantly reduced frequency of binge eating and weight control behaviours other than vomiting, and there was no change in the group on the waiting list. Full remission was achieved in five (24%) of the group assigned to cognitive behavioural treatment, nine (22%) of the group who used the manual, and two (11%) of the group on the waiting list. CONCLUSIONS--A self directed treatment manual may be a useful first intervention in the treatment of bulimia nervosa.