The purpose of this study was to define the content of the requisite knowledge of pathophysiology, clinical microbiology, and mechanisms and effects of drugs needed for clinical knowledge for nursing practice. Contents of knowledge on pathological physiology, clinical microbiology, and mechanisms and effects of drugs were constructed from syllabus of basic nursing subjects in 4 colleges of nursing, and textbooks. The degree of need of 72 items was measured with a 4 point scale. The subjects of this study were college-graduated 136 nurses from seven university hospitals in Seoul and three in Chonnam Province, Kyungbook Province, and Inchon. They have been working at internal medicine ward, surgical ward, intensive care unit, obstetrics and gynecology ward, pediatrics warn, opthalmology ward, ear, nose, and throat ward, emergency room, rehabilitation ward, cancer ward, and hospice ward. The results were as follows : 1. The highest scored items of the knowledge of pathophysiology, clinical microbiology, and mechanisms and effects of drugs necessary for nursing practice were side effects of drugs, anticoagulants, mechanisms of drugs, antihypertensive drugs, tolerance and addiction of drugs, interactions among drugs, hospital infection in the order of importance. The lowest scored item was structure of microrganisms. 2. The highest order of need according to unit was repair in tissue injury unit, definitionㆍetiologyㆍclassification of inflammation in inflammation unit, trasplantation and immunologic response in alterations in immunity unit, thrombus and thrombosis in disorders of cardiovascular function unit, gene disorders in genetic disorders unit, hospital infection in infection unit, virus in microrganisms unit, side reactions of drugs in introduction unit, anticonvulsants in drugs for central nervous system unit, local anesthesia in anesthesia unit, anticoagulants in drugs for cardiovascular system unit, anti-inflammatory drugs in antibiotics unit, anti-ulcer drugs in drugs for digestive system unit, and bronchodilators in drugs for respiratory system unit. 3. The common content of the knowledge of pathophysiology, clinical microbiology, and mechanisms and effects of drugs needed for all clinical areas in nursing were side effects of drugs, anticoagulants, interactions among drugs, and hospital infection. However, the degree of need of each pathological physiology, clinical microbiology, and mechanisms and effects of drugs was different depending on clinical areas. 4. Significant differences in the knowledge of pathophysiology, clinical microbiology, and mechanisms and effects of drugs necessary for nursing practice such as tissue changes due to injurious stimuli, degenerative changes of tissue, alterations in metabolism of carbohydrates, ischemia, hyperemia and congestion, hospital infection, structure of microorganism, classification of microorganism, bacteria, virus, antidepressants, antipsychotic drugs, antiemetic drugs, antiparkinsonism drugs, antianxiety drugs, antibiotics, tuberculostatics, antiviral drugs, antifungal drugs, parasiticides, antiulcer drugs, antidiarrheais, and anti constipation drugs were shown according to the work area. 5. Significant differences in the knowledge of pathophysiology, clinical microbiology, and mechanisms and effects of drugs necessary for nursing practice such as transplantation and immunologic response, alterations in the metabolism of uric acid, structure of microorganism, classification of microorganism, immunosuppresants, drugs for congestive heart failure were demonstrated according to the duration of work. Based on these findings, all the 72 items constructed by Korean Academic Society of Basic Nursing Science should be included as contents of the knowledge of pathophysiology, clinical microbiology, and mechanisms and effects of drugs.