Throughout the history of dialysis, four bioethical principles -beneficence, nonmaleficence, autonomy and justice -have been weighted differently based upon changing forces of technologic innovation, resource limitation, and societal values. In the 1960s, a committee of lay people in Seattle attempted to fairly distribute a limited number of maintenance hemodialysis stations guided by considerations of justice. As technology advanced and dialysis was funded under an amendment to the Social Security Act in 1972, focus shifted to providing dialysis for all in need while balancing the burdens of treatment and quality of life, supported by the concepts of beneficence and nonmaleficence. At the end of the last century, the importance of patient preferences and personal values became paramount in medical decisions, reflecting a focus on the principle of autonomy. More recently, greater recognition that health care financial resources are limited makes fair allocation more pressing, again highlighting the importance of distributive justice. The varying application and prioritization of these four principles to both policy and clinical decisions in the United States over the last 50 years makes the history of hemodialysis an instructive platform for understanding principlist bioethics. As medical technology evolves in a landscape of changing personal and societal values, a comprehensive understanding of an ethical framework for evaluating appropriate use of medical interventions enables the clinician to systematically negotiate and optimize difficult ethical situations.