Protein drugs have become an important class ofbiotherapeutics in the past two decades in fulfilling unmet medical needs.These drugs are given to patients generally by injection.All the mAb drugs approved in the US market are exclusively injectable products.Elimination of the need for invasive injection is highly desirable to patients,especially children.However,market surveys show very limited use of non-parenteral route for protein drug administration.This is because the physicochemical properties of most proteins,having a large molecular size and complex 3-dimensional structure,limit their rapid and extensive absorption across biological membranes.In addition,they are susceptible to rapid enzymatic degradation in various biological tissues,further limiting their bioavailability.With these challenging obstacles,efforts have been fbcused on the development of both non-invasive and less-invasive protein drug delivery systems.This presentation will discuss technologies current available or under development potentially to be used for non-invasive and less-invasive delivery of protein drugs as well as future trends.