Data on mood stabilizers other than lithium as augmentors in SSRI failures are sparse. Carbamazepine (Steinacher et al, 2002) and valproate (Barbee et al, 2002) have been used. Given our recent preliminary results of phenytoin's efficacy in unipolar depression (Nemets et al, 2005) and its analogy to lithium as a mood stabilizer, it seems important to study phenytoin as a possible augmentation of SSRI failures.