The ketogenic diet (KD) is a form of therapy for seizures that involves a brief period of fasting followed by a very carefully controlled high fat-low protein and carbohydrate diet. Studies suggest it is useful in children whose seizures could not be controlled by any of the medicines available. This study is designed to test, in a carefully controlled fashion, how well the diet works in children with "drop" seizures. Children who experience 15 or more drop seizures each day, despite having used at least two medications, may be eligible to participate. This study requires children to undergo periods of fasting and to maintain a carefully controlled diet. Parents of participating children monitor their children's diets and keep daily meal and seizure diaries.