Abstract: Second-order derivative UV spectroscopy was used to measure the transfer of befunolol - HCl across full - thickness rabbit skin in vitro. The effect of penetration enhancers, azone-PG and PEG-400, on permeation course of befunolol-HCl was studied. A type of horizontal diffusion cell was employed. Permeability coefficients were measured in normal saline and in solutions containing the enhancing agents. The results indicated that befunolol - HCl may be an interesting candidate for transdermal administration and azone-PG highly and significantly increases the skin permeation of the drug in the solvent System tested.