Background- There are several studies which have proven there being different stressors in the intensive care unit (ICU). The aim of this study was to evaluate physical and psychological stressors after cardiac surgery in ICU. Methods- This study was conducted by using Intensive Care Unit Environmental Stressor Scale (ICUESS) in 100 patients consecutively after open heart surgery. Data collection was obtained by a questionnaire with 35 items, which scored from (1) not stressful to (4) very stressful. Results- According to ranking, important stressors were: thirst (3.14), pain (3.10), having tubes in the nose or mouth (3.06), being tied down by tubes (2.92), lack of self-control (2.80) and not being able to sleep (2.76), respectively. Conclusion- In conclusion the ICU stay is a difficult experience, which could impact on physical and psychological status of the patients during recovery (Iranian Heart Journal 2003; 4 (2,3): 20-23).