In order to reduce systemic side effects following oral administration, flurbiprofen was formulated as transdermal gels consisting of the drug, poloxamer 407 and ethanol in buffer solutions. The effect of formulation variables in the preparation of flurbiprofen gels on skin permeation of the drug was evaluated using Keshary-Chien diffusion cells fitted with excised rat skins. The permeation rate of flurbiprofen through rat skin was directly proportional to initial drug concentration (between 0.1% and 1.0%) in the gel while it was inversely proportional to poloxamer 407 concentration (between 17.5% and 25%). The skin permeation of flurbiprofen was substantially influenced by the gel pH between 3 and 7, exhibiting a maximum at pH 4. The concentration effect of ethanol on the permeation of the drug was negligible in the concentration range of $10{sim}20%$.