An in-vitro method was developed to investigate the iontophoretic transports of salicylic acid and sodium salicylate through rat skin.A linear increase was recorded with the intensification of the applied current in the observed salicylate flux.The steady-state flux also slightly increased (apparently linearly) with greater donor concentrations, but it was reduced when competitive ions (NaCl) were added to the donor chamber.By employing a direct current of 3V and identical solution, the iontophoretic flux enhancement ratios (flux with current/flux without current) of 3.1 in the case of salicylic acid and 17.7 in the case of sodium salicylate were calculated.These results suggest that iontophoresis might be a convenient way for ionized drug species to achieve constant and readily controllable transdermal delivery.Transport rates might be optimized through adjustment of the donor ionic composition and utilization of current densities.