OBJECTIVE To describe the clinical presentation of the refeeding syndrome and highlight the dangers of performing nutritional rehabilitation too rapidly in a severely malnourished patient. METHODS Retrospective case review of adolescents admitted with anorexia nervosa who developed the refeeding syndrome. RESULTS Between July 1993 and July 1994, 3 of 48 adolescent females developed the refeeding syndrome. While the cardiac complications occurred in the first week of refeeding, the delirium characteristic of this syndrome occurred later and was more variably related to hypophosphatemia. METHODS Refeeding malnourished patients with anorexia nervosa can be associated with hypophosphatemia, cardiac arrhythmia and delirium. Refeeding patients with anorexia nervosa who are < 70% of ideal body weight should proceed with caution, and the caloric prescription should be increased gradually. Supplemental phosphorus should be commenced early and serum levels maintained above 3.0 mg/dL. Cardiac and neurologic events associated with refeeding are most likely to occur within the first weeks, justifying close monitoring of electrolyte and cardiac status.