summary Two girls, 16 and 18 years old, with anorexia nervosa developed generalized convulsion as a result of drinking excessive amounts of water. The neurological symptoms disappeared, but the girls held on to their excessive drinking habits, despite psychoeducation. Although fluid restriction is known to be a major problem for anorexia nervosa patients within the context of extreme fasting, one should realize that these patients can also run the risk of water intoxication following excessive water intake. Therefore all patients should be questioned explicitly about their daily fluid intake. In the case of polydipsia, the patient's blood should be tested and serum electrolytes should be measured. Patients should be given psychoeducation in order to make them more aware of the possible dangers of excessive water intake.