The haematological features of 48 patients with anorexia nervosa were studied in a retrospective fashion, showing a mild hypocellularity with anaemia, thrombocytopenia and granulocytopenia, particularly prominent in male anorectics, but a normal amount of lymphocytes. There was a highly significant association between the degree of weight deficit (in % of ideal body weight) and seriousness of haematological changes, which were all reversible with improvement in nutritional status.