Recently, in order to improve drug permeation through the skin, penetration enhancers have attracted a great deal of interest in increasing percutaneous absorption. Natural compounds like terpenes have been suggested as promising non-toxic, non-irritating transdermal penetration enhancers. This investigation aimed to study the effect of extract and essential oil of Eryngium bungei (as a traditional anti-inflammatory and antinociceptive) on the transdermal absorption of piroxicam. The stable gel was chosen and enhancing effects of plant extract and essential oil with different concentrations (0.5 - 3.0 and 0.25 - 5.0 % w/w respectively) on the permeation of piroxicam were evaluated. The results showed that the greatest enhancement of the skin transport occurs at the highest concentration of the enhancer (P < 0.01). The most outstanding penetration enhancer was plant essential oil in 5 % w/w, providing an almost 9.17-fold increase in permeability coefficient of piroxicam.