Purpose: The purpose of this study was to analyze changes in the work patterns of nurses working in tertiary hospitals in Seoul, Korea Method: Structured self-administered questionnaires were sent to the nursing department of each hospital, and distributed to nurses. The questionnaires were designed to identity changes in work patterns, frequency of contact inside & between departments, and interpersonal relationship inside & between departments. And also variables for analysis included the followings ; acknowledgement of convenience, information applicability, willingness to participate in, and job satisfaction after implementation of a Hospital Information System. A total of 249 nurses from 13 hospitals replied. Results: Changes in direct nursing time showed the most improvement and the frequency of contact was decreased while interpersonal relationships among coworkers was improved. As most nurses expressed a positive opinion of the HIS including its convenience, and information applicability, their willingness to participate in it and job satisfaction, it can be concluded that the implementation of the HIS has resulted in positive influences in the work patterns of clinical nurses.