The objective of the study was to determine the perceptions of a group of patients on intensive care units' (ICUs) stressors and the perceptions of nurses on ICU patients' stressors in Turkey, and compare the differences in patients' and nurses' perception of the stressors in ICUs. In this descriptive study, 155 patients who were admitted to medical or surgical ICUs and 152 nurses who are employed in the same units of two training and research hospitals in Turkey were enrolled in this study. The ICU Environmental Stressor Scale (ICUESS) was used to determine intensive care stressors. According to total ICUESS mean scores, patients (91.41 +/- 34.91) perceived significantly less stress than the ICU nurses (133.23 +/- 32.20) perceived them to have. Both patients and nurses ranked 'fear of death' as the greatest stressor. Physiological stressors were identified as the most important stressors by both patients and nurses. Patients and nurses in medical ICUs were more affected by stressors than their counterparts in surgical ICUs. Patients with unplanned or emergency admissions perceived higher stress than that of patients with planned admissions. Several factors could help reduce these stressors, such as having familiar arrangements, humane ICU environment, individual patient assessments and appropriate nursing interventions. Copyright (C) 2010 John Wiley & Sons, Ltd.