Solid lipid nanoparticles (SLNs) have attracted increasing attention during recent years. Due to their unique size dependent properties, lipid nanoparticles offer possibilities to develop new therapeutics. The ability to incorporate drugs into nanoparticles offers a new prototype in drug delivery thus realizing the dual goal of both controlled release and site-specific drug delivery. Drug delivery to the skin is widely used for local and systemic delivery and has potential to be improved by application of nanoparticulate formulations. If investigated appropriately, solid lipid nanoparticles may open new opportunities in therapy of complex diseases which is difficult to treat.