SUMMARY.We report the biochemical results in 90 women presenting to an eating disorders clinic: 61 who had bulimia, 22 with anorexia nervosa and seven unclassified. The results were compared with 30 control women. The group of women with an eating disorder had significantly higher concentrations of total CO 2 , calcium, AST, ALT. ALP, albumin and cholesterol and significantly lower concentrations of potassium, chloride and phosphate in the plasma. The elevated calcium could be accounted for in part by an increase in total CO 2 and an increase in albumin. Hypokalaemia was strongly associated with self-induced vomiting and laxative abuse. Biochemical abnormalities occurred in both forms of eating disorders; however. hypercholesterolaemia was more common in anorexia nervosa and abnormal liver enzymes were more common in bulimia.Anorexia ncrvosa and bulimia arc psychosomatic conditions with associated abnormal behaviour related to weight control. 1 The most notable feature of anorexia nervosa is marked weight loss and maintenance of low body weight. 2 Bulimia is characterised by episodes of binge eating 'and severe weight fluctuation.: ': 4 A range of weight-controlling behaviours are used by both anorexia nervosa and bulimia patients, including self-induced vomiting, laxative and diuretic abuse, starvation and dieting. I. 3. 4 The diagnosis is now believed to be more common than previously thought. with an incidence in the Australian young female population of I'Yc, with anorexia nervosa and in the order of 10% with bulimia."There are considerable data available on the biochemical changes associated with anorexia nervosa." These have usually been reported in ill or hospitalised patients who might be expected to have significant metabolic derangement. The association of hypokalaemic, hypochloraemic metabolic alkalosis on the basis of self-induced vomiting, purgative or diuretic abuse with anorexia nervosa has been implicated