3D printed microneedles have been fabricated using stereolithography (SLA) though a layer – by – layer deposition of a biocompatible photopolymerized resin. SLA allowed the printing of various microneedle geometries with excellent quality and reproducibility. The technology can be easily adopted for the printing of solid or hollow microneedles for the delivery of drug substance in a solid or liquid form. Printed structures presented very good piercing capacity with minimal application force and string mechanical properties. Advanced characterization techniques (e.g. OCT, micro – CT) provided excellent understanding of the microneedles performance. In vivo animal trials of model drug molecules proved the potential of 3D printed microneedles compared to subcutaneous injections. Clinical findings showed fast onset action and longer duration of the administrated doses. .