The feasibility studies on the transdermal drug delivery systems have been performed to avoid the systemic side-effects and gastric disorders that could be occurred due to the transient high blood concentration after oral administration of antidepressants such as venlafaxine HCl and citalopram. When surfactants of tween $80^{(R)}$ and plasticizer of diethyl phthalate were combined with citalopram-ethylene vinyl acetate (EVA) matrix, the permeation of citalopram showed the best enhancement. As well as, venlafaxine HCl gels were prepared using carbomer, oleic acid and/or propylene glycol to enhance the skin permeation of venlafaxine HCl. The citalopram-EVA matrix containing tween $80^{(R)}$ and diethyl phthalate as permeation enhancers might be a good transdermal delivery system for providing sustained plasma concentrations of citalopram. Also, venlafaxine HCl showed the possibility to be enhanced skin permeation in the formulation of gels with carbomer including penetration enhancer, oleic acid and/or propylene glycol.