Twenty-five years ago, a groundbreaking paper from Tsukuba University in Japan was published, identifying the sequence of the endothelin gene and peptide (Nature 332, 411-415, 1988). This work opened the way for the discovery of the endothelin receptors and the development of orally active endothelin receptor antagonists (ERAs). Today, ERAs are part of medical therapy of patients around the world for the treatment of pulmonary arterial hypertension. Since the discovery of endothelin, about 1000 papers per year have been published, with more than 27,000 articles available today. Many important and break-through findings presented in the endothelin conferences have been published in the conferences' proceedings. Endothelin XIII is the proceedings of the Thirteenth International Conference on Endothelin, held at Tokyo Campus of Tsukuba University, Japan, in September 2013. At the conference, the 25th anniversary of endothelin's discovery was celebrated and articles produced from data presented at the conference are compiled in this Special Issue of Life Sciences. Endothelin XIII includes more than fifty articles, including review articles by experts in the field and numerous original research articles. As the Editors of this special issue, we are proud to present Endothelin XIII and wish the field continued growth for the benefit of patients and for the advancement of biomedical science.