The purpose of this study was to define the content of physiological knowledge needed for clinical nursing practices. Subjects of physiology were classified into 15 areas, and each area was further classified into subareas, resulting in a total of 194 subareas. The degree of importance of each subarea was measured with a 4-point scale. The subjects of this study were 179 nurses of two university hospitals located in Seoul and Inchon. The results were as follows: 1. The areas of physiology necessary for clinical nursing practice as a basic knowledge in the order of importance were : blood, respiratory system and renal physiology , function of the immune system, body fluid and cardiovascular system, body temperature, endocrine physiology and gastrointestinal physiology. However, the degree of importance for reproductive physiology, neurophysiology, energy and metabolism, cell and cell membrane physiology, muscular physiology and special sense was relatively low. 2. The most important content of physiology for all clinical areas in nursing was blood physiology. However, the degree of importance for each physiology area was different depending on clinical areas. 3. Subareas of physiology as a basic knowledge for clinical practice and education in nursing were blood transfusion, blood type, function of red blood cell, white blood cell and platelet, characteristics and function of hemoglobin, composition and function of hemoglobin, composition and function of plasma protein, and mechanism and function of plasma protein, and mechanism of blood coagulation and anticoagulation. In conclusion, areas of physiology necessary for clinical nursing practice were blood, respiratory system and renal physiology, function of immune, body fluid and cardiovascular system, body temperature, endocrine physiology and gastrointestinal physiology. However, the degree of importance for each physiology area was different depending on clinical areas in nursing.