Transdermal perfusion of a large protein is reported for the first time, using a nanoemulsion of bovine serum albumin (66 kDa) of 160 nm prepared by a solid-in-oil (S/O) process. Molecular dynamics simulations confirmed skin permeation by these formulations, with integration of the protein into the lipid bilayers. These results demonstrate the real possibility of delivering large proteins transdermally for a range of medical and cosmetic applications. (C) 2013 Elsevier B.V. All rights reserved.