BACKGROUND: The experience of patients under mechanical ventilation in the intensive care unit is described as complex and multifaceted, but an overarching and in-depth understanding of the experience is still missing. AIM: To provide an in-depth analysis and synthesis of patients' experience when being mechanically ventilated in intensive care units. METHODS: We conducted a meta-synthesis according to the methodological recommendations of Sandelowski and Barroso. Our systematic literature search in Medline, CINAHL, and Cochrane was complemented by hand and citation searches. We included only qualitative studies with a rich description of conscious patients' experience under mechanical ventilation. Studies on children, step-down units, noninvasive ventilation and non-scientific journal articles were excluded. After the title, abstract and full-text screening by three reviewers, we performed initial, axial and selective coding and in-depth analysis in MAXQDA. The synthesis was supported by multiple discussion rounds. RESULTS: Of the 2,563 records identified, 20 studies were included in our synthesis. This revealed the central phenomenon of patients being observers of their own lives. They are yearning for a stable picture of reality and developing various situation-specific needs. Finally, patients are finding ways to deal with the situation. These concepts are interwoven in time and are experienced repeatedly in different dimensions. CONCLUSION: Patients under mechanical ventilation are highly perceptive. Healthcare professionals are particularly responsible for patients. They should reflect on their role in intensive care and must be sensitized to patients' differentiated experience. Registration, Protocol: https://doi.org/10.17605/OSF.IO/G8Q6X.