BACKGROUND: The critical care experience is particularly stressful for patients, which can result in a number of physiological and psychological consequences, including haemodynamic instability, increased pain, agitation and delirium, leading to prolonged mechanical ventilation, length of stay and subsequent complications. Massage therapy encompasses different techniques to promote relaxation and to counter stress, therefore potentially affecting several patients' outcomes. AIMS: To systematically review evidence on the effects of massage on outcomes of adult critically ill patients. The outcome measures included pain, vital signs (VS), haemodynamic measurements, level of consciousness, sleep quality, muscle tension, anxiety, feelings of calm and relaxation, coping, arterial blood gases and serum biomarkers. METHOD: This was a systematic review based on focused literature searches (PubMed, CINAHL, Scopus, EMBASE-Ovid databases, Google Scholar). The Cochrane Collaboration's tool was used to assess the risk of bias. Eligibility criteria included published experimental and quasi-experimental studies reporting on the physiological and psychological outcomes of critically ill patients. RESULTS: Based on the selection criteria, 12 studies were included in the review. The main findings are as follows: 8 of 12 studies used randomized control designs with high internal validity, and there was a high level of evidence of favourable effects with respect to improvements in VS and a reduction in pain and anxiety. Outcomes that need to be more rigorously pursued include quality of sleep, analgesic and sedative dosages and level of consciousness. CONCLUSION: The results suggest that massage interventions can have positive effects on critically ill patients' outcomes. However, there are several gaps in the literature, along with methodological limitations, that require further consideration in critical care settings. RELEVANCE TO CLINICAL PRACTICE: The results of this systematic review can inform implementation of massage interventions in critical care, which can be challenging as a result of several barriers.