The talk is a popular science lecture on medicinal chemistry and will describe how new medicines are designed in the modern era. Starting with a historical perspective , the way drugs interact at a molecular level to bring about a therapeutic effect will be explained using prominent historical examples, going on to describe how this understanding is applied in modern medicinal chemistry to design new medicines. This will be illustrated with notable recent examples from AstraZeneca programmes. The talk will also outline some of the challenges the future holds for the industry. The intention is that the talk will contain sufficient technical content to make it meaningful but will be pitched at a level to make it understandable to those not familiar with the discipline or and with a limited chemistry background. The intended audience is prospective chemistry students wanting to know more about a medicinal chemistry career and members of the public interested in how medicines are discovered and how they work