Immobilization of patients utilizing rigid spine boards (RSB) is standard practice in the management of trauma patients. Pressure ulcers (PU) have been associated with prolonged immobilization. The possibility exists that PU formation may begin when the patient is initially immobilized, the effects not fully recognized because of limited research on the direct tissue effects of prolonged immobilization. Near-infrared spectroscopy is an emerging tool to measure peripheral tissue oxygenation (StO2). The purpose of this pilot study was to study the effects of prolonged spinal immobilization on sacral tissue oxygenation of healthy volunteers. This cross-sectional study measured tissue oxygenation (StO2) in 73 volunteers at baseline and then after 30 minutes of immobilization on a RSB at two sites, the sacrum and a control site not subjected to direct pressure. Data were analyzed utilizing within-subjects analysis of variance. There was a significant increase in the StO2 percentage at the sacral (intervention) area following immobilization, p < .001, rpb = .48. No significant change in oxygenation was noted at the control site. An increase in oxygenation of sacral tissue following immobilization was an unexpected finding and may be a result of initial, rapid tissue reperfusion at the time of pressure release and the inability of this methodology to detect hypoperfusion during tissue compression.