The study investigates exposure to stress by respondents working in an Intensive Care Unit (ICU) and differences in using three instruments to measure stress. The survey was conducted from September to October 2018 in Dubrava Clinical Hospital in the ICU unit, with forty-one (41) healthcare professionals. Three forms of testing were set up: self-evaluation of stress, measurements of physiological indicators, and cortisol levels. The results show a statistically significant difference in mean cortisol levels, with the first sample much higher than other samples. There were significant interactions between skin conduction (SC) and stress levels, where all participants exhibited increases in SC. Heart rate variability (HRV) shows a slight correlation with stress levels in the group possessing substantially more stress experience. Although some differences were observed, all stress elements for professionals working in ICUs indicates that they cope well with stressful situations