Poly(ADP-ribose) polymerase-1 (PARP-1) has been an actively pursued drug discovery target for almost 3 decades. Often referred to as the "guardian angel of DNA", this abundant nuclear enzyme has been the focus of over 20 medicinal chemistry programs in a wide range of therapeutic areas encompassing stroke, cardiac ischemia, cancer, inflammation, and diabetes. Despite the great therapeutic potential for this target and the tremendous academic and industrial efforts dedicated to it, only recently have PARP-1 inhibitors made headway in clinical trials. Recent results from several PARP-1 inhibitors in phase II clinical trials for cancer therapy have attracted the attention of national media. Of the several potential therapeutic indications for PARP-1 inhibitors, the two major areas that hold the most promise are ischemia and cancer. This review is structured to provide the readers with a brief summary of the rationale for PARP-1 as a therapeutic target, to explain the PARP-1 inhibitor pharmacophore, and to provide an update on the progress of the PARP-1 drug discovery programs. This Perspective will offer a historical account of the critical PARP-1 publications that instilled the interest of the biopharmaceutical industry in the late 1980s and early 1990s. Furthermore, it will discuss why PARP-1 received so much attention in the late 1990s and early 2000s followed by the slight decline in the medicinal chemistry efforts today. The major PARP-1 medicinal chemistry programs will be highlighted focusing on the lead generation, lead optimization, candidate selection, and clinical progress. Many aspects of the biological functions of PARP-1 fall outside the scope of this medicinal chemistry review, and readers are referred to relevant citations for those. The 30 years of medicinal chemistry on this topic have also afforded some excellent medicinal chemistry reviews, most of which predated the disclosure of clinical candidate structures and recent clinical trial results.