In these patients, the substitution of topiramate for valproate resulted in significant weight loss. Mr. A, with bipolar disorder, experienced no loss of thymoleptic efficacy; Ms. B, with unipolar depression and impulsivity, experienced increasing depression and anxiety. Anxiety has been reported as an adverse effect of topiramate (1). Like other thymoleptic anticonvulsants, topiramate has significant effects on γ-aminobytyric acid function (2)), but the mechanism of its effects on weight is unknown. Further study should clarify topiramate’s utility in treating mood disorders.