As the hospitalized patients will be facing new stress situation due to change of his environment from home to hospital, it will be very important to understand the psychological stress experienced by hospital patients not only for helping patients in the process of recovery from illness but also fulfilling the objective of comprehensive nursing care by understanding the needs of the patients. There Is no doubt that it would be very helpful for trentment of patients as well as for improvement of nursing care if we know more about psychological needs of patients and give them adequate support to meet these needs. The study to find out the causes and degree of stress events experienced by hospitalized patients, with the objective of instituting improvement of nursing care program based on the needs of patients, was conducted during the month of September 1974 with 60 patients randomly selected from those admitted to medical and surgical wards at Yonsei Medical Center in that period. The questionnaire form included 36 questions which are considered to be stress events for hospital patients, and was devided into five areas namely, such events related to 1) disease itself, 2) hospital environment, 3) nursing care and treatment, 4) communication and human relations, and 5) family and economic problems. The results of the study were as follows: 1. It was confirmed that hospitalization considered to be a stress producing factor and most patients perceived the admission to hospital as a stress factor. 2. According to the rating scale, it was found that degree of perceived stress shows a variation according to the source of stress producing event. 3. No significant differences in the mean values were observed statistically with the perceived stress levels according to demographic and other variables of patients related to hospitalization. 4. Among the questions related to disease itself, "Admission for surgery" was perceived most frequently as a stress event (97.14%) by patients. 5. With regard to the questions related to hospital environment, "death of the patient roommate" was the most serious stress event perceived by patients (90%) and "living with hospital regulations" was considered to be less serious stress event (23.33%). 6. As for the questions related to nursing care and treatment, "limitation of freedom" was perceived as a stress factor most frequently (70.91%) by the patients and "worry for wrong treatment" turned out to be less frequent stress event (50.0%). 7. As for the questions related to communication and human relations, "difficulty to meet doctors when wanted" appeared to be the most frequent stress event by the respondents (75. 86%), followed by "no explanation about treatment or examination" (75.0%) and "no explanation about nursing care procedures" (71.66%). 8. With regard to the questions related to family and economic problems, "inadequate finances ior tamily living due to hospitalization" and "high cost oi hospitalization" were the most frequent cause of stress mentioned by the pa:ients. (80.0%). 9. As a result of application of the slepwise regression analysis, it was found that about 89% was explained by those events associated will) disease itself, hospital environment and family and economic problems. By adding those events related to "nursing care and treatment" and"communication and human relation", 100% of stress associated with hospilalization was explained.