This article discusses the prevalence of uncertainty in healthcare, emphasizing the impact it has on evidence-based medicine, shared decision making, and patient-centered care. The authors argue that the lack of a unified concept of uncertainty in health has hindered our ability to understand its effects; to address this, the authors synthesize literature from communication, decision science, engineering, health services research, and psychology to propose a three-dimensional taxonomy of uncertainty in healthcare based on source, issue, and locus. The taxonomy is designed to provide a more organized approach to understanding and managing uncertainty in healthcare, offering insights into its nature, prognosis, analysis, and management strategies.