In 2010, only a decade since microRNAs were discovered in humans, the first patient was treated with a microRNA drug, miravirsen, for hepatitis C virus (HCV) infection. This chapter opens with the discovery that HCV contained binding sites for miR−122, an abundant liver-specific microRNA. It looks at the research showing how the virus hijacks miR−122 to replicate, and the groundbreaking drug development programme that took advantage of this to create the world’s first medicine to target a microRNA. It covers some of the microRNA-based therapies further back in the drug development pipeline, discussing the relative strengths but also the risks of this approach. It explores the method to target microRNAs, including recent developments to disrupt single microRNA–target interactions to create precision microRNA therapies, and the viruses being commandeered to deliver microRNA treatments into specific cell types in the body. Lastly, it looks at how new microRNAs are being identified and considers the future of microRNA-based treatments, focussing on prospects for neurological disorders and reflecting on how, by listening to patients, we can create better and safer medicines.