Precision Medicine has evolved in the last decade to offer incredible promise by delivering improved individual outcomes for patients. While technology and science has contributed to advancing Precision Medicine at an accelerated pace, regulatory bodies have needed to quickly adapt to address the new challenges presented by these novel scientific applications. In addition to ensuring patient safety, regulatory bodies are heralding enhanced therapeutic effectiveness delivered by new targeted therapies and devices by offering breakthrough designations and expedited regulatory pathways. A key development that is front and center of Precision Medicine is the companion diagnostic to guide patient therapy. Drug and diagnostic manufacturers must collaborate effectively to overcome significant hurdles to identify and co-develop a companion diagnostic which is then contemporaneously approved with its corresponding drug product. This presentation will introduce regulatory concepts affiliated with co-development of drug and diagnostic, as well as outline the regulatory challenges in realizing Precision Medicine.