Background: Intensive care units (ICUs) are a health environment particularly affected by suffering at work. These units treat patients with serious medical conditions with an immediate life-threatening risk in an emergency situation. As a result, caregivers are confronted intensively and repeatedly with an extreme clinic. Currently, many tools used to assess caregiver stress are not as close as possible to the professional experience and do not take into account the subjective perception of stressors. The objective of this qualitative study is to rely directly on the way professionals perceive their work, and to identify the specificity of stress factors in ICU. Methods: We conducted individual clinical interviews with 166 intensive care providers (84 nurses and 81 physicians) in four countries (France, Italy, Spain, Canada). During the interview, they were asked to express their work experiences. The interviews were recorded, and then fully transcribed, and analysed using interpretative phenomenological analysis. Findings: The qualitative analysis identified 99 stressors divided into eight main stress source themes. The identification of these stress factors highlights stress dimensions that seem more specific to ICU such as dealing with ethical and moral-related situations, risk management issues. Discussion: All dimensions of stress are not well represented in the stress scales most commonly used in ICU (e.g. JCQ, ERI, NSS, NWI). This study shows us the need to develop a stress tool specific to ICU.