Although the ketogenic diet has been used in the therapy for epilepsy for more than 50 years, there are few studies concerned with the effects of this diet on the central nervous system. Recent attempts to unravel the biochemical effects of the ketogenic diet on the brain seem to be a fruitful approach to understanding how the ketogenic diet causes anticonvulsant effects. Another exciting approach is the development of animal models in which various effects of the diet can be correlated with changes in seizure protection. It would be useful to determine whether the diet produces any neurophysiological effects that could account for some, or all, of its antiseizure properties. Finally, the efficacy of the diet is impressive. It is likely that the ketogenic diet will never be of major therapeutic importance because of the expense and commitment required of the patient and the family. Nevertheless, it appears obvious that continued study of a therapy which seems to work so well will give us some valuable clues as to the mechanism of seizures and their control. Further investigations into the mechanism of action of the ketogenic diet should be encouraged.