In this study, drug carrier properties through skin and penetration enhancement effects of carbon nanotubes (CNTs) are presented. Multi-walled and double-walled carbon nanotubes were used. Penetration enhancement into the skin following passive diffusion and iontophoresis were determined. Possible solubility enhancement effects and drug adsorption properties of CNTs were investigated. CNTs were found to be a useful drug carrier system and they can provide a high loading and enhanced transdermal penetration for especially hydrophobic drugs. The electroconductive nature of CNTs allows easy application of iontophoresis and the additional advantage of CNTs appears to be using them as electrodes.