Recent advances in biotechnology have led to a rapid expansion in the use of protein based therapeutics. Translation of pharmacological activity in vitro to a clinically effective therapeutic requires a suitable drug delivery system. Iontophoresis is a non invasive technique and offers a promising alternative. Chapter 1 presents a novel method of visualizing transdermal protein distribution after iontophoresis. Chapter 2, 3 and 4 (RNAse-A, RNAse-T1 and hbFGF respectively) discusses the possibility of delivering medium size proteins into and across the skin. Chapter 5, 6 and 7 (Lysozyme, IFN-β-1b and IGF-1) describes the factors which can limit the transdermal delivery of proteins. Chapter 8 talks about the computational methods to calculate various three-dimensional molecular properties of proteins which were then correlated with electrotransport data. Chapter 9 of this thesis is focused on briefly reviewing different stratum corneum ablation techniques, which can be used to further improve iontophoretic delivery.