To determine the natural history of delayed gastric emptying of solid foods in anorexia nervosa (AN), gastric emptying was assessed by scintigraphy in 20 consecutive inpatients; eight had restrictive AN, ten had both AN and bulimia nervosa (BN), and two BN alone. Initial gastric half-emptying time (HET) exceeded 110 min (the upper limit of normal for the laboratory) in 16; their body mass index ranged from 11.7 to 18.1. HET showed a significant negative correlation with body mass (r = 0.71; p less than 0.001) but not age, duration of illness or use of psychotropic medication. Fourteen patients with prolonged emptying were retested; HET improved in nine of 12 retested at one month (p = 0.0005) but none showed a change in the lag phase of emptying. All four patients retested a further one to two months later achieved a HET less than 110 min. Fourteen patients reached a body mass index of 16.3 during treatment and HET improved to better than 110 min in all but one of these. However, normalisation occurred while body mass was still subnormal (less than 20.3) and with amenorrhea still present. This study shows that delayed gastric emptying in AN improves quite rapidly as feeding recommences; thus the motility disturbance is secondary to restriction in food intake and is not fundamental to the disorder.