Occupational stress in nursing and its causes and effects have been the areas of research interest for many years. Critical Care Units are highly technological areas where nurses are required to make rapid life sustaining and life saving decisions. Therefore, Comparative descriptive study was conducted among 100 CCU nurses working in Medical College Hospitals, Kerala to assess the sources and levels of stress. The results revealed that the nurses working in Government hospital generally reported more stress than private hospitals. The commonest stress dimensions were caring for patients, general job requirements and workload for both the sector nurses though the order differed.