This book demonstrates the potential of urine as a biomarker resource for early disease detection, covering the related theory, strategies, tools and findings. Biomarker is measurable changes associated with the disease. Blood, as a critical part of the 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, accumulates early and small changes of the body without homeostatic control.