The human nail penetration of the antifungal ciclopirox was determined for marketed gel containing 0.77% of ciclopirox, an experimental gel containing 2% of ciclopirox, and a marketed lacquer containing 8% of ciclopirox. After 14 days dosing, unabsorbed drug remaining on the surface, drug within the infection-prone area, and the amount that had penetrated through the nail were determined. Ciclopirox delivery into and through the nail was significantly greater from the marketed gel, than from either the experimental gel or the nail lacquer (p < 0.05). In addition, the surface nail contained more unabsorbed drug from the lacquer. Further, the drug penetrating into and through the nail was also greater from the marketed gel, leading to a higher Calculated Efficacy Coefficient for the marketed gel, than from the marketed lacquer or the experimental gel. The formulation plays an important role in the enhancement of ciclopirox permeation into and through the human nail plate, and the concentration of ciclopirox in the formulation was not a factor in determining penetration.