Many research groups and pharmaceutical companies worldwide are focusing on the use of microporation devices, and microneedles (MNs) are one of them. MNs are gaining significant interest in today's transdermal drug delivery research and development and a wide variety of strategies for the microfabrication of MNs have been reported. It was originally started with the microfabrication of silicon MNs and the technology was later extended towards the microfabrication of metal and polymeric MN arrays. In this chapter, we have described different microfabrication techniques of MN arrays for transdermal drug delivery applications. We have described in detail the design, fabrication and materials utilised in MN fabrication. Also, an account for optimisation of the MN design is given in order to address its effective application in transdermal drug delivery.