In anorexia nervosa, amenorrhoea and endocrine disturbance make pregnancy unlikely while the patient's weight is low. Bulimics may conceive at quite a low weight, and anorexics who have regained weight may become pregnant but typically relapse following delivery (Crisp, 1980). Anorexia has also been reported following termination of pregnancy (Thomas & Harris, 1982). Cases of onset of anorexia nervosa with weight loss during pregnancy are rare in the literature, although there are isolated reports (e.g. Weinfeld et al, 1977; Strimling, 1984). Strimling described a treated anorexic who restarted dieting during pregnancy in response to weight gain before she realised that she was pregnant. We report on a schoolgirl who became pregnant at 14 years, whose anorexia began when she was 5 months pregnant and whose pregnancy was not discovered until she was in labour.