The epistemological status of health science, natural science, and clinical knowledge is explored. It is shown that 'health science', a term increasingly used in association with the clinical knowledge of the therapies, nursing, and other health occupations, is not fully a science in the sense of the natural sciences. It is rather a hybrid which relates applications of natural science, behavioral science, and the humanities to problems in health. The same may be said of clinical knowledge which entails, as essentials, humanistic considerations involving the personal concerns of the patient, in addition to the more evident external aspects of diagnosis and treatment. The recent introduction of the term 'health science' reflects scientism in its approach to health issues. It also reflects confusion about the nature of clinical knowledge.