This study examined reasons why patients discontinue the ketogenic diet. A total of 46 children placed on the ketogenic diet between November 1994 and August 1996 were followed prospectively. Reasons for discontinuing the diet prior to 6 months were analyzed. Nineteen (41%) children discontinued the diet for either medical or nonmedical reasons. Nonmedical reasons were caregiver issues and patients' unwillingness to follow the diet. Noncompliance was more common in older children. The ketogenic diet, while effective, is a very stringent diet. Nonmedical reasons for discontinuation are as common as the traditional medical reasons of lack of efficacy or complications.