Precision medicine is a multibillion-dollar industry poised to continue growing in coming years. Understanding its role in health care delivery and health care research is of vital significance to the future of medicine. Imprecise Medicine proposes a definition of precision health that reconceptualizes major case studies from the history of bioethics^&#8212such as the Tuskegee Syphilis study and Willowbrook^&#8212while also applying the theory to contemporary issues. Imprecise Medicine develops this definition in depth, demonstrating how it can inform both research agendas and clinical practice while clarifying the boundaries of precision health. Delston contends that certain applications of precision medicine are ethically untenable^&#8212particularly when they rest on flawed conceptions of socially constructed categories, take advantage of research participants, or exacerbate inequities in access to medical innovation.Building on her previous book Medical Sexism, Delston defines medical bias and demonstrates how it shapes precision health delivery and research. This approach provides a unified theory, understanding medical bias as a hierarchy and offering practical methods for avoiding it. Finally, Delston explores how integrating ethical considerations into precision health can expand research opportunities and improve study design. Biases such as medical sexism and medical racism have led to major gaps in knowledge, and addressing these biases can both meet ethical obligations and open new directions for research.Ultimately, Imprecise Medicine presents a framework for reducing bias while centering patient autonomy, equity, privacy, and confidentiality, offering a clear path forward for precision health.