Purpose: Comprehensive nursing care services are provided for patient-centered nursing care in Korea. This study was conducted to compare differences in the frequency and elapsed time of nursing activities between comprehensive nursing care units and general medical-surgical units. Methods: This is a descriptive study design using direct observation of nursing care activities. A time and motion study on the frequency and elapsed time of nursing activities provided by nurses was conducted in the comprehensive nursing care units and general units of two small-to-medium sized hospitals. Data were collected for 64 hours in each hospital, through a two-way method using a checklist and a camera recorder. Results: The total number of nursing activities, activities provided per patient and patient safety care including clinical assessment and treatment were higher in the comprehensive nursing care units compared to general units. We found similar findings regarding the duration of nursing activities. Conclusion: Comprehensive nursing care units provide patient-centered nursing care and have a broader range of nursing activities for patient safety than general units. Assessments conducted to meet nursing needs and to promote safe nurse staffing should reflect the characteristics of the nursing tasks performed in comprehensive nursing care units.