Body image perception was measured in 50 women with bulima nervosa and 19 age and weight matched female controls, using a visual size estimation apparatus. Both groups overestimated body widths, but not the width of a neutral object, and whilst there was a trend for bulimics to overestimate more than controls this did not reach significance. The part of the body most overestimated corresponded to the part most disliked in only a third of both groups. The bulimics without a previous history of anorexia nervosa overestimated body width more than those with such a history; this may be related to the fact that the former had a significantly greater weight index. Bulimics who were within 5% of mean-matched population weight overestimated body width less than the others, this difference reaching significance when compared with the heavier groups; a similar, but non-significant, trend was demonstrated in controls. This may be linked to a greater dissatisfaction with body size. Duration of illness, frequency of bingeing and self-induced vomiting were not shown significantly to alter body size estimation. The bulimics who completed a 10-session outpatient treatment programme subsequently demonstrated a significant decrease in overestimation of waist and hip width.