Purpose:  The postoperative monitoring of digit replants continues to be a challenge.  Current objective methods of digit monitoring have not been widely adopted due to complexity or lack of sensitivity.  Tissue oxygen tension measures the pressure gradient between capillary oxygen delivery and tissue consumption thus providing an index of oxygen cellular availability.  A clinical study was undertaken to evaluate non-invasive monitoring of tissue oxygenation using near-infrared spectroscopy in post-operative digit revascularization and replantation. Methods:  Seventeen patients were enrolled and twenty-four digits monitored in one institute.  There were 15 males and 2 females with an average age of 45 years old (13-79).  Digits were monitored by clinical exam, fluorescein, and the ViOptix ODISsey^TM tissue oxygenation probe at 1-2 hour intervals for 24-48 hours.  Results:  Twenty-three digits survived and one digit failed.  In the survival digits, the fluorescein and tissue oxygenation (StO2) readings were similar to the control digit readings.  There were no significant differences between fluorescein and StO2, or between StO2 readings for control and survival digits.  The digit that failed was a combination right hand crush injury and third digit amputation.  In this digit, both fluorescein and StO2 readings were lower in the failed compared to control digit immediately post-op and for the remainder of the hospital course.  The mean StO2 values for this digit were significantly reduced, ranging 30-50% lower than those obtained for the control digit (p<0.0002). There were no complications associated with fluorescein or tissue oxygenation measurements.  Conclusion:  Near-infrared spectroscopy measurement of tissue oxygenation correlates with fluorescein monitoring, digit perfusion, and clinical outcome.  This non-invasive monitoring is easy, reliable, safe, and potentially useful in post-operative monitoring of digit replantation.