Purpose: This study was conducted to investigate degree of stress level in CCU patients, and to give a baseline data in developing nursing intervention program to reduce the stress. Method: Subjects of this study were the 100 hospitalized patients of C University Hospital in Seoul City from February to December 2003. The collected data was analyzed by using the SAS program: t-test, Scheffé test, and ANOVA analysis were employed to find differences in stress level. Result: The highest stress factor was ‘Concern’, and next were ‘Dependency & limitation’, ‘Uncertainty’, ‘Treatment procedure’, ‘Sleep disturbance’, ‘Environment’ in order. The perceived stress level of CCU patients was 1.65 scores; the highest scored item was ‘have to void urine and feces on the bed’, next were ‘have to use the toilet bowel lying on the bed’ in order. The stress level according to characteristics of the subjects was significantly different with the marital status, the presence of religion, the hospitalized days, the economic status, and the admission experience. Conclusion: The stress level of patients in the coronary care unit was high in concern of a disease, family and economic state, in limitation and dependency, and in uncertainty about prognosis of a disease. Further researches are necessary to develop and apply the intervention method of reducing stress level of CCU patients. In addition studies on family members of CCU patients are also recommended.