Abstract : Human growth hormone (hGH) is one of the most important large protein drugs, which is secreted by the pituitary gland. Deficiency in this hormone causes stunned growth and mental retardation. Recently, replacement therapies including hGH have become one of the most popular anti-aging treatments especially in cosmocauticals. In this study, the transdermal route as an alternative route for in vitro hGH hormone delivery was investigated. hGH was formulated using various cyclodextrins (CDs). The enhancing effect of CDs on hGH skin permeation was investigated in vitro using Franz diffusion cells. The results suggest the enhancing effect of CDs on in vitro transdermal delivery hGH.