Introduction: Near infrared spectroscopy (NIRS) is a method for non-invasive continuous monitoring of muscle tissue oxygen saturation (StO2). In trauma patients normal parameters of macrocirculation does not exclude the possibility of disturbances in regional perfusion. It has been suggested that StO2 levels can detect microcirculatory disturbances early and select patients in states of compensated shock. The purpose of this literature review is to sum up the current literature on the use of NIRS as a diagnostic tool during hypovolemia in trauma patients. Material and methods: The following search words “(Near infrared spectroscopy OR NIRS) AND (hypovolemia OR shock)” used in the PubMed database generated 221 articles and lead to the inclusion of 25 articles and reviews. In addition textbooks have been used and the references of the selected articles have been reviewed in order to find additional information. Results and discussion: In the reviewed articles, low StO2 values have been associated with negative outcomes among trauma patients. Likewise, the need of transfusions and other lifesaving interventions have been related to lower StO2 values. However, the StO2 values did not manage to differentiate between milder levels of shock. None of the studies used NIRS as a tool to guide treatment. A major obstacle when comparing studies has been the lack of uniformity regarding application of the NIRS device and study protocols. Conclusion: NIRS technology, although promising, does not yet have enough support in literature to be routinely used as a diagnostic tool among hypovolemic trauma patients. Further studies with greater statistical power are required to determine NIRS future role in trauma care.