This book demonstrates the potential of urine as a biomarker resource for early disease detection, covering the related theory, strategies, tools and findings. Biomarkers are measurable changes associated with diseases. Blood, as a critical part of its internal environment, is closely monitored and controlled by the body to maintain homeostasis, especially in the early stages of diseases. In contrast, urine, as a form of waste excreted by the body, collects a variety of substance changes. Accordingly, urine can offer an ideal resource for early biomarker discovery. In addition, urine is more stable than blood in vitro, and is easy to store and analyze. The book discusses exciting preliminary applications of urine biomarkers for diseases affecting major biological systems. Its main goal is to make scientists, clinicians and medical companies aware of this important, exciting, undeveloped, and profitable field.