Purpose : This study was conducted to provide for a basic resource, which can be used to set up a efficient management system in Cardiac Surgery Intensive Care Units(CSICU). Method: 1) Questionnaires were administered and observation methods were used, to examine the nursing activities performed in the CSICU after having reviewed related literatures and a review by the experts. Thus, the nursing activities were designating 254 activities and classified into 28 categories. 2)The 22 nurses in the 2 CSICUs filled out questionnaires about nursing activities from 12 April, 2002 to 17 April, 2002. The frequency of the nursing activities in the 28 categories counted and new nursing activities added by directly observing 12 nurses by two trained research staffs for 4 day. 3)In terms of validity, the 264 nursing activities were analysed by the 25 experts. As a result, 231 nursing activities were found valid and remained as appropriate nursing activities to be used for the careful analysis of the nursing activities in CSICUs. Result: The 22 categories are as below: assessment, monitoring, respiration management, nutrition management, elimination/drainage management, mobility management, sanitation management, safety management, temperature management, specimens collection, preparation and assistance of treatment, skin/wound management, infection management, medication management, education^{port, dying patient care, recording}keeping, supplies management, environment management, communications, evaluations, professional development Conclusion : The manifest job description of the staff nurse will contribute to improving the efficiency of the nursing activities and to reducing the role conflicts among the medical staffs.